Atmospheric real-time ionization

Abstract

In this ambient ionization experimental embodiment, the abundance of background chemicals relative to the ions of interest is reduced by pulsing the carrier gas used to generate the excited species that are directed toward the sample. The excited species are directed toward the sample in stages, reducing the overall abundance of background chemicals introduced into the ionization region. In this ambient ionization experimental embodiment, the combination of stepping the sample in front of the excited species and pulsing the carrier gas used to generate the excited species increases the sensitivity of detection.

Description

Technical Field

[0001] The present invention relates to a method and a device for chemical analysis of molecules that are ionized in an ambient atmosphere by pulsed introduction of a carrier gas.

Background Art

[0002] Analysis of target molecules in an ambient atmosphere in a laboratory or in the field can be performed by using ionized species to convert the target molecules into ions and directing or ejecting the ions towards a spectrometer. However, the ambient atmosphere in a laboratory or in the field may contain many detectable "background chemicals". These background chemicals can vary depending on the local environment. For example, trace chemicals present in laboratory air can include solvents, dust particles, aerosols, counterions, and chemicals used in synthesis or extraction. Furthermore, the background can include chemicals from the activities of humans, animals, bacteria, viruses, or fungi, including those from the presence of spectrometer operators / scientists, including respiration, perfumes, fragrances, mouthwashes, cosmetics, sweating, flatulence, bacterial gases, and bacterial odors. The presence of one or more of any of these can create a persistent background. If the background becomes excessive, the process of ambient ionization and ion detection of target molecules becomes inefficient, and the target molecules are either not detectable or are detected in such small amounts that detection is obscured by the detection of background chemicals.

[0003] Trace chemicals present in the sample of interest are present in the ionization region but are not of interest, so they can also be regarded as background chemicals. These include chemicals derived from the sample container, solvent residues, chemicals that are normally present but not important for the characterization of the sample, and chemicals introduced into the air surrounding the ionized species, including those derived from human activities such as solvents or other nearby analytical efforts. For example, in a urine sample, the metabolite creatinine (a chemical waste product produced by muscle metabolism) is easily ionized and detected using a spectrometer. The kidneys can filter other waste products, including creatinine and urea, from the circulating blood and remove them from the body through urination. Therefore, both of these compounds (creatinine and urea) are present as background chemicals during the analysis of human-derived liquids. Furthermore, since it is difficult to extract urea itself from urine, the analysis of abused drugs in workplace urine drug tests is usually performed using chromatographic materials to separate urea from the target molecule. The chromatographic material allows urea to be directed to the waste while retarding the passage of larger drug molecules. In the absence of urea, larger drug molecules are ionized in the ambient atmosphere and are easily detected after entering the spectrometer.

[0004] Solvent effects can also contribute to background chemicals such as solvents used to dissolve the sample, such as dimethyl sulfoxide (DMSO), and chemicals added to the sample to promote pH changes or ionization buffering can also contribute to the background.

[0005] In theory and practice, removing background chemicals prior to ambient ionization reduces background chemical ions, i.e., chemical noise, and improves sensitivity to the target molecule. Summary of the Invention

[0006] In embodiments of the present invention in ambient ionization experiments, pulsing the carrier gas used to generate ionized species can be used to increase the ionization of target molecules, thereby lowering the detection limit. In embodiments of the present invention involving ambient ionization experiments, jumping from one position and pulsing the carrier gas used to generate ionized species can be used to increase the ionization of target molecules, thereby lowering the detection limit.

Brief Description of the Drawings

[0007] All direct analysis real-time (DART) atmospheric pressure ionization (API) measurements were performed at 300 °C unless otherwise specified. All samples were spotted using a volumetric pipettor, the TTP Labtech Mosquito. All mass spectrometry was performed on a THERMO SCIENTIFIC™ Q-EXACTIVE™ mass spectrometer. Various embodiments of the present invention will be described in detail based on the following figures.

[0008]

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DETAILED DESCRIPTION OF THE INVENTION

[0009] The abbreviations are as follows. API = Atmospheric Pressure Ionization, CIE = Continuous Ionization Experiment, DART = Direct Analysis in Real Time, DESI = Desorption Electrospray Ionization, DMS = Differential Mobility Spectrometer, ESI = Electrospray Ionization, GIS = Gas Ion Separator, HE = Hybrid Experiment, RS = Reaction Species, PE = Pulse Experiment, SIM = Single Ion Monitoring, TIC = Total Ion Current.

[0010] The definitions of specific terms used hereinafter are as follows.

[0011] The transitional phrase "comprising" is synonymous with "including", "containing", or "characterized by", is inclusive or open-ended, and does not exclude additional, unrecited elements or method steps.

[0012] The transitional phrase "consisting of" excludes elements, steps, or components not specified in the claims, but does not exclude additional components or steps not related to the invention, such as impurities normally associated with a composition.

[0013] The transitional phrase "consisting essentially of" limits the scope of the claim to those that do not materially affect the basic and novel characteristics of the invention to a particular material or step and those recited in the claim.

[0014] The term "gas ion separator (GIS)" is used to refer to a device that separates ions from one or both of neutral molecules and neutral atoms and enables preconcentration of the ions and their transfer to an analysis system. The term "inlet tube" is used to refer to the low-vacuum side of the GIS. The term "outlet tube" is used to refer to the high-vacuum side of the GIS. In various embodiments of the present invention, the tube included can be the inlet tube. Active ionization refers to a process of using an atmospheric analyzer that does not utilize radioactive nuclei to ionize analyte ions. A capacitive surface is a surface that can be charged with an electric potential. If the electric potential applied to the surface remains during the typical duration of an experiment and the surface potential exceeds 50% of the electric potential applied to the surface, the surface can be charged with an electric potential. Atmospheric pressure vacuum is approximately 760 torr. Here, "about" encompasses pressures in the range of less than 10 1 atmospheric pressure = 7.6×10 3 torr to pressures up to 10 -1 atmospheric pressure = 7.6×10 1 torr. A vacuum of less than 10 -3 torr constitutes a high vacuum. Here, "about" encompasses pressures in the range of less than 5×10 -3 torr to pressures up to 5×10 -6 torr. A vacuum of less than 10 -6 torr constitutes a very high vacuum. Here, "about" encompasses pressures in the range of less than 5×10 -6 torr to pressures up to 5×10 -9 torr. In the following, the phrase "high vacuum" encompasses high vacuum and very high vacuum.

[0015] The term "contact" is used to refer to a process by which molecules of a sample in one or more of the gas phase, liquid phase, and solid phase are adsorbed, absorbed, or chemically bonded to a surface.

[0016] As a result of the process, when substrate molecules are adsorbed, absorbed, or chemically bonded to the surface, the grid is "coated" with the substrate. When beads are adsorbed, absorbed, or chemically bonded to the grid, the grid can be coated. When nanobeads are adsorbed, absorbed, or chemically bonded to the grid, the grid can be coated.

[0017] The term "filament" means one or more of a loop of wire, a segment of wire, a metal ribbon, a metal strand or non-insulated wire, an animal tendon, paper, perforated paper, a fiber, a cloth, silica, fused silica, plastic, plastic foam, polymer, Teflon, Teflon impregnated with polymer, cellulose, and filaments coated and impregnated with a hydrophobic support material. In various embodiments of the present invention, the filament has a diameter of from about 50 microns to about 2 mm. When measuring the diameter of the filament, the "about" indicates plus or minus 20 percent. In one embodiment of the present invention, the length of the filament is from about 1 mm to about 25 mm. When measuring the length of the filament, the "about" indicates plus or minus 20 percent.

[0018] The term "orientation" means the position of the mesh relative to another section of the mesh or relative to the grid or sample holder. In one embodiment of the present invention, the mesh, grid, or sample holder can be attached to an X-Y translation stage to enable the precise orientation of the sample spotted on the mesh with respect to the ionizing species. The control electronics and stepper motor driver for the X-Y stage can be attached directly to the box housing the X-Y translation stage, while the microcontroller for controlling the orientation can be attached separately.

[0019] The term "proximity" means the position of a mesh or region on the mesh relative to another mesh or other region on the mesh.

[0020] The term "alignment" means when an area of the mesh (e.g., the proximal area) aligns with the mesh to deliver heat from the mesh to the proximal area of the tine.

[0021] The term "contacting" means the attachment or contact of an object or surface, such as sampling of the surface, with an area of the mesh.

[0022] The shape of the mesh can be a cylinder, an elliptical cylinder, a long square block, a long rectangular block, or a long and thin surface.

[0023] The term "hole" refers to a hollow space in an otherwise solid object with an opening that allows light and / or particles to pass through an otherwise solid object. The hole can be circular, elliptical, pear-shaped, slit-shaped, or polygonal (including triangles, squares, rectangles, pentagons, hexagons, heptagons, etc.).

[0024] The term "high temperature" in the context of high temperature atoms and / or high temperature molecules, etc., means species having a velocity corresponding to a temperature above the ambient (273K) temperature. In one embodiment of the present invention, the high temperature species have velocities corresponding to temperatures of 300K, 400K, and 500K.

[0025] The term "continuous flow" carrier gas means that the flow of the carrier gas into the discharge chamber is adjusted in a constant pattern. The term "hybrid flow" carrier gas means that the flow of the carrier gas into the discharge chamber is pulsed when the linear rail is moving the mesh at measured time intervals, and otherwise there is no flow of the carrier gas into the discharge chamber. The term "pulse flow" carrier gas means that the flow of the carrier gas into the discharge chamber is pulsed when the linear rail stops for a certain time, and otherwise there is no flow of the carrier gas into the discharge chamber.

[0026] The term "corona discharge" means a discharge that occurs at a relatively high gas pressure (e.g., atmospheric pressure) in a very non-uniform electric field (e.g., by placing a thin wire inside a metal cylinder having a radius much larger than that of the wire). The electric field is high enough to cause ionization of the gas surrounding the wire, but not high enough to cause electrical breakdown or arc discharge to a nearby conductor. The term "arc discharge" means a discharge that depends on thermionic emission of electrons from the electrodes supporting the arc and is characterized by a lower voltage than glow discharge but has a strong current. The term "glow discharge" means a discharge generated by secondary electron emission.

[0027] The term "first atmospheric pressure chamber" means a chamber at approximately atmospheric pressure.

[0028] The term "discharge" means one or more of corona discharge, arc discharge, and glow discharge.

[0029] The metal contains one or more elements consisting of lithium, beryllium, boron, carbon, nitrogen, oxygen, sodium, magnesium, aluminum, silicon, phosphorus, sulfur, potassium, calcium, scandium, titanium, vanadium, chromium, manganese, iron, cobalt, nickel, copper, zinc, gallium, germanium, arsenic, selenium, rubidium, strontium, yttrium, zirconium, niobium, molybdenum, technetium, ruthenium, rhodium, palladium, silver, cadmium, indium, tin, antimony, tellurium, terbium, cesium, barium, lanthanum, cerium, praseodymium, neodymium, promethium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, lutetium, hafnium, tantalum, tungsten, rhenium, osmium, iridium, platinum, gold, mercury, thallium, lead, bismuth, polonium, francium, radium. Therefore, the metal includes, for example, nickel-titanium alloys known as nitinol, or chromium-iron alloys used to manufacture stainless steel.

[0030] The plastic contains one or more of polystyrene, high impact polystyrene, polypropylene, polycarbonate, low density polyethylene, high density polyethylene, polypropylene, acrylonitrile butadiene styrene, polyphenylene ether alloyed with high impact polystyrene, expanded polystyrene, polyphenylene ether, and polystyrene impregnated with pentane, a blend of polyphenylene ether impregnated with pentane or polyethylene and polypropylene and polystyrene.

[0031] The polymer contains a material synthesized from one or more reagents selected from the group consisting of styrene, propylene, carbonate, ethylene, acrylonitrile, butadiene, vinyl chloride, vinyl fluoride, ethylene terephthalate, terephthalate, dimethyl terephthalate, bis-beta terephthalate, naphthalene dicarboxylic acid, 4-hydroxybenzoic acid, 6-hydroxy-2-naphthoic acid, monoethylene glycol (1,2-ethanediol), cyclohexylene dimethanol, 1,4-butanediol, 1,3-butanediol, polyester, cyclohexane dimethanol, terephthalic acid, isophthalic acid, methylamine, ethylamine, ethanolamine, dimethylamine, hexamethylamine diamine (hexane-1,6-diamine), pentamethylene diamine, methylethanolamine, trimethylamine, aziridine, piperidine, N-methylpiperidine, formaldehyde anhydride, phenol, bisphenol A, cyclohexanone, trioxane, dioxolane, ethylene oxide, adipoyl chloride, adipic acid, adipic acid (hexanedioic acid), sebacic acid, glycolic acid, lactide, caprolactone, aminocaproic acid and / or a blend of two or more materials synthesized from the polymerization of these reagents.

[0032] The plastic foam is a polymer or plastic with trapped air bubbles, including polyurethane, expanded polystyrene, phenolic foam, XPS foam, and quantum foam.

[0033] "Mesh" means one or more of two or more connected filaments, two or more connected strings, forms, perforated papers, screens, paper screens, plastic screens, fiber screens, cloth screens, polymer screens, silica screens, Teflon (registered trademark) (polytetrafluoroethylene (PVDF)) screens, polymer-impregnated Teflon screens, and cellulose screens. In various embodiments of the present invention, the mesh includes one or more of three or more connected filaments, three or more connected strings, meshes, forms, grids, perforated papers, screens, plastic screens, fiber screens, cloth, and polymer screens. In one embodiment of the present invention, the mesh can have about 10 filaments per 1 mm. In another embodiment of the present invention, the mesh can have about 20 filaments per 1 mm. In additional embodiments of the present invention, the mesh can have about 30 filaments per 1 mm. In alternative embodiments of the present invention, the mesh can have about 100 filaments per 1 mm. When designing the number of filaments per 1 mm, "about" indicates plus or minus 20 percent.

[0034] The "base layer" is a polymer, metal, and / or plastic.

[0035] A "pulse generator" is a device such as a voltage-controlled pulse generator that can be adapted to generate short (about 0.1 second, where "about" means plus or minus 10 percent) pulses of a valve, pressure regulator, or carrier gas.

[0036] A "carrier gas" is a gas that can generate excited species in the presence of a discharge at atmospheric pressure.

[0037] A "grid" is a substrate in which gaps, spaces, or holes are punched or otherwise introduced into the substrate, or windows or sections are cut out or otherwise removed from the substrate, and a mesh is inserted into the removed windows or sections. In one embodiment of the present invention, the grid can have a thickness between a lower limit of about 1 micron and an upper limit of about 1 cm. In this range, "about" means plus or minus 20 percent.

[0038] The term "background chemical" means "matrix molecule" and / or "introduced contaminant".

[0039] The term "target molecule" or "analyte" means naturally occurring species (e.g., caffeine, cocaine, tetrahydrocannabinol), or synthetic molecules introduced into a biological system, e.g., pharmaceuticals (e.g., lidocaine, methadone, sildenafil, lipitor, enalapril and their derivatives), and recreational drugs (e.g., morphine, heroin, methamphetamine, etc. and their derivatives).

[0040] The term "introduced contaminant" means a chemical substance that becomes associated with a sample during sample preparation and / or sample analysis. Introduced contaminants can be suspended in the air or present in or on the surface with which the sample is in contact. For example, perfumes or deodorants can be associated with sample analysis and analyzed during sample analysis. Alternatively, phthalate esters present in plastic tubes used to process a sample can leach from the plastic tube into the sample and thereby be introduced into the sample.

[0041] The term "background chemical" means "matrix molecule" and / or "introduced contaminant".

[0042] The term "ion-suppressing molecule" means a background chemical that suppresses the ionization of the molecule of interest and / or generates background species that ionize in such a way as to impair the detection of the molecule of interest.

[0043] The terms "background ion" or "background species" refer to ions formed from background chemicals. Background species can include the molecule itself, adducts of the molecule, fragments of the molecule, or combinations thereof.

[0044] The term "matrix effect" refers to a decrease in the ionization of the molecule of interest due to the presence of background species. The matrix effect occurs when the background chemical suppresses the ionization of the molecule of interest and / or when background species ionize in such a way as to impair the molecule of interest. Without wishing to be bound by theory, in the former case, it is thought that the molecule of interest is not ionized by the presence of the background chemical. In the latter case, the resulting mass spectrum is dominated by background species in such a way as to impair the analysis of the molecule of interest. Background species may suppress and / or mask the ionization of the molecule of interest.

[0045] The term "analytical amount" refers to an aliquot of the sample being analyzed, for example, applied to a mesh for analysis.

[0046] The term "ion enhancer" means a chemical that inhibits the matrix effect.

[0047] The term "peak abundance" is the number of ions generated. The peak abundance of the protonated molecular ion of a sample is a measure of the number of intact ions of the sample generated (other processes such as cationization can also be a measure of the number of intact ions of the sample generated). The relative peak abundances of two species are the sum of the intensities corresponding to each species.

[0048] DART API CIE The DART API CIE is an analytical method introduced, for example, in QuickStrip and involves presenting a series of samples placed at individual discrete positions on a movable surface. The surface is attached to a holder fixed to a linear rail, and the linear rail enables a constant linear motion (i.e., a fixed speed) to present the samples as a series for analysis. The surface (usually a mesh) includes areas where samples are present and areas where samples are not present. As a result of this linear motion, the samples are presented in front of a static source of ionized species, thereby enabling the scanning (and analysis) of the samples.

[0049] The DART API CIE utilizes a carrier gas that generates ionized species directed towards the surface (e.g., 1536 QuickStrip mesh card). In the DART API CIE operating mode, since the carrier gas is not pulsed, the ionized species are directed towards the surface regardless of whether the sample is presented to the ionized species. Thus, valuable purified carrier gas is wasted (see Figure 3).

[0050] Furthermore, in the DART API CIE mode, background species are generated when the sample is not presented on the surface. Without wishing to be bound by theory, when the ionized species interact with the leading edge (or trailing edge) of the sample, the analyte in the sample is thought to compete with the background chemistry for the charge generated by the ionized species. If the analyte wins this competition event, analyte ions are formed. If the background chemistry wins the competition, background species are formed. Without wishing to be bound by theory, it is thought that the competition is not exclusively won by a particular species but is driven by the proton affinity in positive ionization mode. Without wishing to be bound by theory, it is further thought that if a large number of background species are formed in front of the leading edge, the detection of analyte species formed at the leading edge may be impaired.

[0051] The advantage of the DART API CIE method is that it allows for inaccurate (or non - reproducible) deposition of the sample for analysis. As long as the sample is anywhere in the region bathed in the ionization gas. In the DART API CIE method, ions are generated from both the sample and the background during the experiment by a continuous shower of ionized species.

[0052] DART API PE DART API PE is an analytical method aimed at minimizing the wasteful use of carrier gas by utilizing the accurate deposition of the sample using robotics and the similar accurate presentation of the sample in front of the source that provides a shower of ionized species. While the sample is being moved to a predetermined position, the carrier gas entering the source is turned off, and the ionized species formed by the source are preserved. Although not desired to be constrained by theory, when the carrier gas is turned off, it is thought that the discharge continues, but without the flow of the carrier gas, the ionized species exiting the source are attenuated. Depending on the sample spacing and the time required for sample desorption, a dramatic reduction in the consumption of carrier gas can be observed (see Figure 3). That is, with the accurate deposition and accurate timing of the sample, there is no need to deal with inaccurate (or non - reproducible) deposition of the sample. Therefore, due to the accurate deposition and accurate positioning of the ionized species, there is no need to have a wide beam of ionized species. Instead, a narrow end - cap can be utilized to generate a defined shower of ionized species with a narrower spray pattern (i.e., with a narrower range of impact).

[0053] Although not wishing to be bound by theory, it is believed that background species are only observed when they successfully compete with the analyte present in the sample for charge by presenting a static sample. Since the ionized species interact with the sample, changes in the ion intensity of the analyte may be due to depletion of the background species or analyte species. In embodiments of the present invention, the DART API PE operating mode with a duration pulse is used to optimize the ionization of the analyte, and the duration is 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, or 2.0 seconds. In embodiments of the present invention, the DART API PE mode operating with a 1-second pulse is used to optimize the ionization of the analyte. In embodiments of the present invention, the DART API PE mode operating with a 2-second pulse is used to optimize the ionization of the analyte.

[0054] DART API HE DART API HE is an analytical method aimed at minimizing the wasteful use of carrier gas while maintaining the characteristics of DART API CIE. That is, by turning off the carrier gas while placing the ionized species in the sample area, a similarly dramatic reduction in carrier gas consumption is observed (see Figure 3 of Hybrid 3 mm / sec).

[0055] Carrier gas The DART API in the presence of a carrier gas generates a plasma around the discharge. Lowering the pressure of the carrier gas from about 70 psi to about 0 psi for about 1 second to about 3 seconds also does not adversely affect the plasma stability. In this pressure range, "about" means plus or minus 20 percent. In this time range, "about" means plus or minus 20 percent. Without wishing to be bound by theory, the plasma surrounding the electrode is thought to be held in a region close to a stable plasma. When the carrier gas is not supplied to the plasma, the ionized species do not flow out of the plasma towards the sample. The pulse of the carrier gas is generated by increasing the pressure applied to the carrier gas in a region close to a stable plasma, which forces the ionized species to flow out of the stable plasma generation region towards the sample.

[0056] Helium DART DART is another API method suitable for the analysis of analytes. Various embodiments of the DART API are described in Laramee's U.S. Patent No. 7,112,785 (hereinafter referred to as the '785 patent), which is hereby expressly incorporated by reference in its entirety for all purposes. The '785 patent relates to the desorption ionization of molecules from surfaces, liquids, and vapors using a carrier gas containing reactive species (RS). The DART API can use a large amount of carrier gas. For example, helium is suitable, but other inert gases capable of generating RS can also be used.

[0057] Nitrogen DART The API can ionize analyte molecules and dissolve the analyte without using a solvent. Ionization occurs directly from solids and liquids. Molecules present in the gas phase can also be ionized by reactive species exiting the API. In one embodiment of the present invention, the reactive species utilized can be excited nitrogen atoms or molecules. In one embodiment of the present invention, the reactive species can generate long-lived metastable species to affect analyte molecules at atmospheric pressure, for example, to affect ionization. See U.S. Utility Patent Application No. 16 / 422,339 to inventor Brian D. Musselman, entitled "APPARATUS AND METHOD FOR REDUCING MATRIX EFFECTS," filed May 24, 2019. This is incorporated herein by reference in its entirety and for all purposes.

[0058] Gas-Ion Separator (GIS) In various embodiments of the present invention, devices and methods for transferring analyte ions desorbed from an adsorbent surface to the inlet of a mass spectrometer using an atmospheric analyzer can utilize a GIS. Embodiments of the present invention include devices and methods for collecting analyte ions and / or other analyte species formed within a carrier and transferring them to the inlet of a mass spectrometer.

[0059] In one embodiment of the present invention, one or both of the inlet and outlet of the GIS tube can be made of one or more materials selected from the group consisting of stainless steel, non-magnetic stainless steel, steel, titanium, metal, flexible metal, ceramic, silica glass, plastic, and flexible plastic. In one embodiment of the present invention, the length of the GIS tube can range from 10 millimeters to 10 meters. In one embodiment of the present invention, the GIS tube can be made of a non-woven material. In one embodiment of the present invention, the GIS tube can be made of one or more woven materials.

[0060] In various embodiments of the present invention, a GIS including two or more coaxial tubes with a gap between the tubes and a vacuum applied to the gap region is used to enable sampling of a large amount of carrier gas. In various embodiments of the present invention, the GIS is composed of an inlet tube and an outlet tube. In one embodiment of the present invention, the proximal end of the inlet tube is closest to the adsorbent surface, and the distal end of the inlet tube can be somewhat distant from the proximal end to which a vacuum can be applied. In various embodiments of the present invention, the proximal end of the outlet tube is adjacent to the distal end of the inlet tube, and the distal end of the outlet tube enters the spectroscopic system.

[0061] 90-degree GIS Using robotic sample deposition, the system can deposit sub-microliter volumes of sample in an accurate high-speed X-Y plate orientation for DART API analysis of the sample. Previously, the performance of 90-degree GIS components was impaired by high background and matrix effects. Unexpectedly, when stepping to a fixed position using a pulsed carrier gas source, the 90-degree GIS shows no signs of high background and matrix effects. Thus, the pulsed carrier gas source and stepping to a fixed position enable direct DART API using 90-degree GIS from high-performance robotics without the need to move the sample from the sample deposition robot. Further, the 90-degree GIS can be combined with an extended X-Y plate with a holder. This allows the sample deposited on the QuickStrip mesh to be moved through the desorption ionization region at the distal end of the DART source, such that the sample deposited on the front side of the mesh can be vaporized and ionized very close to the proximal end of the GIS located on the back side of the mesh. The 90-degree GIS can be combined with an extended X-Y plate with a holder. This allows the sample deposited on the QuickStrip mesh to be moved through the desorption ionization region at the distal end of the DART source, such that the sample deposited on the front side of the mesh can be vaporized and ionized very close to the proximal end of the GIS located on the back side of the mesh.

[0062] FIG. 15A is a line drawing of a pipetting robot (1504) with a series of 16 volumetric pipettes (1523) for small samples on the surface of a QuickStrip-96 wire mesh consumable (1532) attached to a sampling stage (1543), as shown in FIG. 16A. When the sample is pipetted to the exact position, the sampling stage is moved to the robot arm, and the robot arm is designed to move the sample through the ionization region of the DART API source and ionize the sample in the PE mode. FIG. 15B is a line drawing of a DART API source (110) mounted in a vertical position with a 2.5 mm outlet cap (118) attached in series with a 90° GIS (140) equipped with an MS (170) instrument, as shown in FIG. 16B. Attempts to perform 90° GIS experiments using the DART API CIE have sometimes been unsuccessful. Without wishing to be bound by theory, the DART API CIE can generate background species, and due to the 90° GIS configuration, these background species are not removed from the ionization region as quickly as in the linear configuration, so competition between the background species and the analyte species is thought to occur.

[0063] FIG. 16A is a pipetting head of a TTP Labtech Mosquito robot (1504) with a series of 16 volumetric pipettes (1523) for small samples on the surface of a QuickStrip-96 wire mesh consumable (1532) attached to a sampling stage (1543). FIG. 16B is a DART API source mounted in a vertical position with a 2.5 mm outlet cap in series with a GIS interface connected at a 90° angle to a mass detector. FIG. 16C is a DART API source mounted in a vertical position with a 2.5 mm outlet cap in series with a GIS interface connected at a 90° angle to a mass detector. FIG. 16D is a DART API source mounted in a vertical position with a 2.5 mm outlet cap in series with a smooth continuous tube surface GIS interface connected at a 90° angle to a mass detector.

[0064] When using DART API PE in a 90-degree GIS configuration, the generation of analyte ions can be made more efficient than with DART API CIE, where pulses of ionized species occur only when a sample is present, and the generation of background species is reduced. As a result of fewer background species, the possibility of intermolecular interactions is reduced. Consequently, when intermolecular interactions are reduced, analyte species can pass through the 90-degree GIS more efficiently.

[0065] The rapid and reproducible desorption and analysis of fentanyl was facilitated by a 90-degree GIS using DART API PE, and all analyte ion species present in the sample were detected. This was also true for ultra-small samples (200 nL), and the deposition of the sample and the position of the sample prior to ionized species were under the control of an accurate robotic system. Therefore, DART API PE with an extended X-Y plate holder enables a combination of DART direct ionization species on the front side of the plate. Without wishing to be bound by theory, the ions generated using a pulsed carrier gas are low in absolute number, reducing the possibility of intermolecular ion-ion interactions and thus are thought to pass through the elbow more efficiently.

[0066] Dimensions of the cap Depending on the distance between the source of the ionized species and the mesh, the spot size of the ionized species affecting the mesh can vary. A cap with a cap hole from which the ionized species are emitted can be used to limit the spot size in the sample. The dimensions of the cap and the cap hole can be selected to adjust the spot size of the ionized species in the sample. The cap (117, 118) can extend by a distance (121) between a lower limit of about 0.1 mm and an upper limit of about 5.0 mm (e.g., 0.2, 0.3, 0.4, and up to 4.5, 4.6, 4.7, 4.8, 4.9 mm), where the about in this range means plus or minus 20 percent. In various embodiments of the present invention, the distance (121) can be continuously adjustable to optimize the scan speed depending on several factors including, for example, the number of samples to be analyzed. The cap hole (119) can take on various shapes including oval, elliptical, rectangular, square, circular. The circular cap hole (119) can have a diameter between a lower limit of about 0.1 mm and an upper limit of about 5.0 mm (e.g., 0.2, 0.3, 0.4, and up to 4.5, 4.6, 4.7, 4.8, 4.9 mm), where the about in this range means plus or minus 20 percent. In the case of a non-circular cap hole (119), the maximum extent of the opening of the cap hole can be between a lower limit of about 0.1 mm and an upper limit of about 5.0 mm (e.g., 0.2, 0.3, 0.4, and up to 4.5, 4.6, 4.7, 4.8, 4.9 mm), where the about in this range means plus or minus 20 percent of the spatial resolution. In various embodiments of the present invention, the cap hole (119) is continuously adjustable to optimize the spot size and spatial resolution, thereby enabling an appropriate selection of carrier gas pulsing and / or scan speed to optimize sensitivity and minimize the generation of background species, contaminants or artifacts.

[0067] In an embodiment of the present invention, as shown in FIG. 2A, for a narrow cap (117) having a hole (119) with a diameter of 1.0 mm, the distance (121) between the distal end (115) of the DART source and the sample (130) was about 2.0 mm. This configuration (a narrow cap with a 1.0 mm diameter hole and a distance to the sample of 2.0 mm) is referred to as a "1.0 mm exit cap". With the 1.0 mm exit cap configuration, it was possible to analyze spots that were 2.25 mm apart (i.e., from adjacent samples). Typically, the 200 nL sample analyzed dried as a spot with a diameter of about 1.1 mm and became a spot about 1.1 mm apart. In this configuration, when using a DART API CIE with a scan speed of 2.5 mm / second, the contribution of species from the observed adjacent samples was minimized (i.e., cross-contamination was minimized). Thus, in one embodiment of the present invention, the spatial resolution at 2.5 mm / second is about 1 mm. In this range, about means plus or minus 20 percent.

[0068] In an alternative embodiment of the present invention, a longer cap (118) having a hole (119) with a diameter of about 2.5 mm and a distance (121) between the distal end (115) of the 1.0 mm DART source and the sample (130) is shown in FIG. 2B. This configuration (a long cap with a 2.5 mm diameter hole and a distance to the sample of 1.0 mm) is referred to as a "2.5 mm exit cap".

[0069] 1536 samples In an embodiment of the present invention, as shown in FIGS. 13 and 14 using a DART API PE with a 2.5 mm exit cap, without observing species from adjacent samples (i.e., without cross-contamination), it was possible to analyze spots formed by applying 200 nL aliquots of xxx samples that were 2.25 mm apart (in the x direction) and 2.25 mm apart (in the y direction) (i.e., from adjacent samples). Thus, in one embodiment of the present invention, the spatial resolution is about 1 mm. In this range, about means plus or minus 20 percent.

[0070] Figure 13A is a DART API PE (equipped with a 2.5 mm outlet cap) mass spectrum for caffeine (SIM 195.1±0.5 Da) present in a 200 nL volume of a mixture of cocaine (1 mg / mL), lidocaine (1 mg / mL), and methadone (1 mg / mL) applied to a mesh sample presented in a 1536 sample plate format. Figure 13B is a DART API PE (equipped with a 2.5 mm outlet cap) mass spectrum for lidocaine (SIM 235.2±0.5 Da) present in a 200 nL volume of a mixture of caffeine (1 mg / mL), cocaine (1 mg / mL), and methadone (1 mg / mL) applied to a mesh sample presented in a 1536 sample plate format. Figure 13C is a DART API PE (equipped with a 2.5 mm outlet cap) mass spectrum for cocaine (SIM 304.3±0.5 Da) present in a 200 nL volume of a mixture of caffeine (1 mg / mL), lidocaine (1 mg / mL), and methadone (1 mg / mL) applied to a mesh sample presented in a 1536 sample plate format. Figure 13D is a DART API PE (equipped with a 2.5 mm outlet cap) mass spectrum for methadone (SIM 310.2±0.5 Da) present in a 200 nL volume of a mixture of caffeine (1 mg / mL), lidocaine (1 mg / mL), and cocaine (1 mg / mL) applied to a mesh sample presented in a 1536 sample plate format.

[0071] Figure 14A is a DART API PE (with a 2.5 mm outlet cap) mass chromatogram of caffeine (SIM 195.1±0.5 Da) present in a 200 nL volume of a mixture of cocaine (1 mg / mL), lidocaine (1 mg / mL), and methadone (1 mg / mL) applied to a mesh (12 replicates at positions 1 - 12) sample presented in a 1536 sample plate format. Figure 14B is a DART API PE (with a 2.5 mm outlet cap) mass chromatogram of lidocaine (SIM 235.2±0.5 Da) present in a 200 nL volume of a mixture of caffeine (1 mg / mL), cocaine (1 mg / mL), and methadone (1 mg / mL) applied to a mesh (12 replicates at positions 1 - 12) sample presented in a 1536 sample plate format. Figure 14C is a DART API PE (with a 2.5 mm outlet cap) mass chromatogram of cocaine (SIM 304.3±0.5 Da) present in a 200 nL volume of a mixture of caffeine (1 mg / mL), lidocaine (1 mg / mL), and methadone (1 mg / mL) applied to a mesh (12 replicates at positions 1 - 12) sample presented in a 1536 sample plate format. Figure 14D is a DART API PE (with a 2.5 mm outlet cap) mass chromatogram of methadone (SIM 310.2±0.5 Da) present in a 200 nL volume of a mixture of caffeine (1 mg / mL), lidocaine (1 mg / mL), and cocaine (1 mg / mL) applied to a mesh (12 replicates at positions 1 - 12) sample presented in a 1536 sample plate format. Figure 14E is a DART API PE (with a 2.5 mm outlet cap) TIC of methadone (1 mg / mL), caffeine (1 mg / mL), lidocaine (1 mg / mL), and cocaine (1 mg / mL) applied to a mesh (12 replicates at positions 1 - 12) sample presented in a 1536 sample plate format.

[0072] API The API process involves an initial action of ionizing gas by means of a discharge. In plasma-based APIs, the discharge of inert gases such as nitrogen, argon, helium, etc. forms ionized gas molecules, atoms, and metastable molecules and atoms. These charged high-energy particles exit the ionization source and interact with the molecules in the air containing background chemicals. Ions are formed during this interaction. These ions are typically (i) intact protonated or deprotonated molecules such as, for example, NO + , O2 - , H3O + etc., (ii) clusters of water molecules with one proton, and (iii) ions derived from the molecules present in the ambient air containing background chemicals. The API becomes an analytical tool when these protonated water molecules interact with the analyte present in the air, resulting in the transfer of a proton to the analyte. The analyte can enter the ionized species by introducing the analyte as a gas, liquid, or solid placed in the path of the products of the gas discharge. Two forms of the API are atmospheric pressure chemical ionization (APCI), which uses a discharge between a high-voltage needle and the surface to which the sample is applied, and direct analysis in real time (DART) (DART API), which uses a discharge and a heated gas to desorb the sample from the surface to atmospheric pressure. In the absence of a sample, the molecules present in the ambient air are ionized and detected, generating a mass spectrum.

[0073] Often, when a sample is intentionally introduced into the ionized species, ions are formed that are easily measured using a spectrometer placed in close proximity to the API site.

[0074] In the case of biological samples, the specific molecules present have a very high proton affinity. That is, the intentional introduction of ionized species results in ionization and the formation of an ionized dimer containing two molecules and one proton. High proton affinity molecules can also bind to another molecule or several closely related molecules to form a mixed dimer or tetramer in protonated form. Due to the affinity of these molecules for protons, the use of ionization methods as an analytical method is prohibited. This is because other target molecules in the sample cannot remain non-ionized and thus cannot be detected using a spectrometer placed in close proximity to the API site. In API experiments, the domination of the resulting spectrum by one molecule or a collection of high proton affinity molecules is generally identified as an experiment with matrix effects.

[0075] Theoretically, during ambient ionization, if the sample being analyzed contains background species that ionize more efficiently than the analyte, the analyte or molecule of interest may not be detected. As the properties of the background chemicals become more competitive, the detection of the molecule of interest is impaired. Although not wishing to be bound by theory, it is thought that as the affinity of the background chemicals for the ionized species increases, the detection of the molecule of interest is impaired and the efficiency of detection of the molecule of interest decreases. This is an manifestation of the "matrix effect", an API condition that can potentially interfere with the use of methods for analysis. There are several background chemicals that cause matrix effects in certain situations. For example, the presence of urea in urine and nicotinamide in tobacco products are examples where the background chemicals dominate the spectrum generated to the point where reliable detection of other chemicals in the sample is hindered.

[0076] In one embodiment of the present invention, the amount of ionized species generated can be increased by changing from a 1.0 mm exit cap to a 2.5 mm exit cap. Similarly, the amount of ionized species generated can be increased by changing from DART API HE or DART API PE to DART API CIE. Unexpectedly, it has been observed that the sensitivity can be increased when using DART API CIE with a 2.5 mm exit cap as compared to DART API PE with a 2.5 mm exit cap. Without wishing to be bound by theory, it is thought that when the use of DART API PE reduces the ionized species, the time packet of the ionized species becomes narrower, the competition time between the analyte species and the background species decreases, and the formation of analyte ions increases. This requires a wider hole and a shorter distance to the sample, suggesting that the reduced ionized species can be compensated for and that the wider hole and / or shorter distance facilitates directing more packets of ionized species towards the sample.

[0077] Figures 2A and 2B show an API source (110) where ionized species exit the distal end of the source through caps (117, 118) and interact with molecules present in the surrounding atmosphere that result in the generation of ions. Ions and neutral gas are drawn into a spectrometer (170) by the action of a vacuum applied to the proximal end of a transfer tube (140) from an ionization region (120) surrounding a sample applied to a surface (130), and a vacuum is applied at the distal end (150) of the transfer tube (140) by either the spectrometer (170) or an external vacuum pump (180). In one embodiment of the present invention, the gas containing ions enters a gas ion separator at its proximal end and moves towards an inlet of an inlet region (160) including a spectrometer inlet tube (165), where it is drawn into the spectrometer (170) by either the vacuum of the spectrometer (170) or a combination of its vacuum and the vacuum of the external pump (180). Analyzing the volume of gas containing ions that passes through the spectrometer inlet tube (165) and enters the volume of the spectrometer (170) enables the detection and characterization of the ions. The mass spectrum generated from a mesh with no sample applied is dominated by ions generated from low-mass molecules present in the atmosphere and residual organic molecules from the production of plastics and other chemicals. In experimental tests, for the introduction of a sample, the gas of interest is directed or the sample of interest is placed on the surface (130), which is then placed in the ionization region (120) between the source (110) and the spectrometer (170), which typically results in an immediate change in the appearance of the spectrum.

[0078] Example 1 Using a MOSQUITO® robot (TTP Labtech, Cambridge, UK), eight samples were deposited onto a first QuickStrip® (IonSense Inc., Saugus, Massachusetts) wire mesh screen using a 12-well format. Samples (200 nL of a mixture of cocaine (0.01 mg / mL), fentanyl (0.01 mg / mL), and codeine (0.01 mg / mL)) were placed at positions 3, 4, 5, 6, 7, 8, 9, and 10 as shown in Figure 1. The first QuickStrip (90) was prepared. A linear rail (20) holding a sample card (40) with a laser-cut stainless steel mesh (50) placed on it was inserted into a blank (30) and set to scan each of the 12 analysis spots (1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12) at a speed of 3 mm / second as shown in Figure 1.

[0079] The first QuickStrip (90) was analyzed in a DART API source using helium as an ionization species set to a temperature of 300 °C to generate precursor ions of drugs of abuse. Figure 4A is a positive DART API CIE (1.0 mm exit cap) mass chromatogram of fentanyl (SIM 337.2 ± 0.5 Da). Figure 4B is a positive DART API DART API CIE (1.0 mm exit cap) mass chromatogram of cocaine (SIM 304.3 ± 0.5 Da). Figure 4C is a positive DART API DART API CIE (1.0 mm exit cap) mass chromatogram of codeine (SIM 300.3 ± 0.5 Da). Figure 4D is a positive DART API DART API CIE (1.0 mm exit cap) TIC trace of the ions formed. Significant TIC was observed at the analysis spots where no sample was applied (1, 2, 11, and 12, see Figure 1), indicating that ionization of molecules present in the environment (such as phthalic acid esters, perfluoroalkanes, etc.) can generate a relatively rich pool of background species that can reduce the efficiency of the ionization process of the target molecule when the sample is introduced into the ionization region. As shown in Figure 10, a comparison of the peak widths in the mass chromatograms of Figure 4A (short dashed line), Figure 4B (long dashed line), Figure 4C (dashed-dotted line) and the TIC peak width in Figure 4D (solid line) shows that the peak in Figure 4D is broader than those observed in Figures 4A - 4C. Furthermore, the intensity of the TIC trace increases at an earlier time than the SIM in Figures 4A - 4C. Although not wishing to be bound by theory, it is thought that short time intervals are observed during which "unrelated ions" (i.e., ions formed from background chemicals not related to the sample) that contribute to the TIC trace are formed. Therefore, it has been proposed that there are background chemicals that form unrelated ions and that they may interact or compete with the sample of the ionization species. Thus, reducing the ability of the background chemical to compete with the sample improves the analytical sensitivity of the sample.

[0080] Example 2 Using the Mosquito robot, the same sample as in Example 1 was deposited onto the second QuickStrip.

[0081] Next, the second QuickStrip was analyzed using a DART API source operated in the same manner as in Example 1, but with an exit cap of 2.5 mm.

[0082] Figure 5A is the positive DART API CIE (2.5 mm exit cap) mass chromatogram of fentanyl (SIM 337.2 ± 0.5 Da). Figure 5B is the positive DART API CIE (2.5 mm exit cap) mass chromatogram of cocaine (SIM 304.3 ± 0.5 Da). Figure 5C is the positive DART API CIE (2.5 mm exit cap) mass chromatogram of codeine (SIM 300.3 ± 0.5 Da). Figure 5D is the positive DART API CIE (2.5 mm exit cap) TIC trace of all ions generated from the mesh as a function of the sample position on the mesh. Comparing the TIC obtained using the 1.0 mm exit cap (Figure 4D) with the TIC obtained using the 2.5 mm exit cap (Figure 5D), it can be seen that the ionization area increases as the cap size increases. The increase in the gas volume exiting the cap and the generation of approximately constant ions from the background and the sample means that there are a large number of background-related ions in the ionization region before the sample is ionized. The generation of ions is approximately constant despite the presence of physical barriers imposed by the metal tines existing between each of the individual positions (see gap 30 between positions 1 - 12 in Figure 1). It is observed that the narrow cap provides more efficient generation of ions for analysis, but since it does not limit the generation of background species, it does not reduce the competition between background species and sample-related ions. Once again, comparing the width of the peaks in the mass chromatograms of Figures 5A - 5C with the width of the peaks in the TIC (Figure 5D), it is shown that there are ions unrelated to the sample before the analysis of each sample, and thus there is a nearly continuous period during which these background chemicals are present and can interact or compete with the ionized species.

[0083] Example 3 Using the Mosquito robot, the same sample as in Example 1 was deposited on the third QuickStrip.

[0084] Next, a third QuickStrip was analyzed using the DART API source operated as in Example 1. In the DART API HE, the sample is presented discontinuously at a location where the ionized species are off before the presentation of the first sample, starting when the sample is presented and moving at 3 mm / sec for 1 second, and then paused until the second sample is presented for analysis. For the analysis, the pulsed gas and movement process are repeated for all 12 samples.

[0085] Figure 6A is the positive DART API HE (1.0 mm outlet cap) mass chromatogram of fentanyl (SIM 337.2 ± 0.5 Da). Figure 6B is the positive DART API HE (1.0 mm outlet cap) mass chromatogram of cocaine (SIM 304.3 ± 0.5 Da). Figure 6C is the positive DART API HE (1.0 mm outlet cap) mass chromatogram of codeine (SIM 300.3 ± 0.5 Da). Figure 6D is the positive DART API HE (1.0 mm outlet cap) TIC trace of all the ions formed. In the analysis of samples, it is assumed that the more samples present, the greater the signal intensity observed. Furthermore, more sample ions can be desorbed by moving the sample through the ionized species as a function of time so that more samples are exposed to the ionization conditions. Both of these assumptions are being questioned by the results presented. With the DART API HE (1.0 mm outlet cap), sample movement occurs with the pressure of the ionized species turned off until the position of the mesh relative to the source is such that the ionized species is directed at the sample. The simultaneous activation of the carrier gas pressure within the ionization source and the movement of the mesh to present the sample occur in a short time. A comparison of the peak widths of the mass chromatograms in Figures 6A, 6B, 6C and the peak width of the TIC (Figure 6D) shows that there are no background chemical-related ions present prior to sample introduction (see Figure 11). That is, there is no nearly continuous period of ions unrelated to the sample present prior to the sample analysis period. Examination of the peak shapes of the mass chromatograms in Figures 5A, 5B, 5C and the TIC (Figure 5D) shows that there are ions unrelated to the sample present when the sample is moving. For example, tailing of each peak is observed, indicating that the sample ions are competing with the background chemical molecules of the ionized species.

[0086] Example 4 Using the Mosquito robot, the same sample as in Example 1 was deposited on the fourth QuickStrip.

[0087] Next, a fourth QuickStrip was analyzed using a DART API source operated in the same manner as in Example 3, but with an exit cap of 2.5 mm.

[0088] Figure 7A is a positive DART API HE (2.5 mm exit cap) mass chromatogram of fentanyl (SIM 337.2 ± 0.5 Da). Figure 7B is a positive DART API HE (2.5 mm exit cap) mass chromatogram of cocaine (SIM 304.3 ± 0.5 Da). Figure 7C is a positive DART API HE (2.5 mm exit cap) mass chromatogram of codeine (SIM 300.3 ± 0.5 Da). Figure 7D is a positive DART API HE (2.5 mm exit cap) TIC trace of all ions formed from the mesh as a function of the sample position on the mesh. Comparing the TIC obtained using a 1.0 mm exit cap (Figure 6D) with the TIC obtained using a 2.5 mm exit cap (Figure 7D), it can be seen that the ionization area increases as the cap size increases. In embodiments of the present invention, the preferential generation of sample-related ions was brought about by the absence of ions before increasing the pressure to flow the ionized species over the mesh. It has been observed that the movement of the sample into the ionized species region before the pressure is increased to direct the ionized species towards the sample improves the generation of sample-related ions. The observation that the peak width increases and the peak tailing of each mass chromatogram increases compared to CIE indicates that the generation of background-related ions is occurring and that those ions are functioning to decrease the generation of sample-related ions.

[0089] Example 5 Using a Mosquito robot, the same sample as in Example 1 was deposited on a fourth QuickStrip.

[0090] Next, the fifth QuickStrip was analyzed using a DART API source operating as in Example 1, i.e., with a 1.0 mm exit cap, but using the DART API PE (i.e., the linear rail was set to jump to each of the 12 analysis spots (1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12) as shown in FIG. 1, pausing for 1 second after each jump, during which helium was pulsed to the DART API source.

[0091] Figure 8A is a positive DART API PE (1.0 mm outlet tip) mass chromatogram of fentanyl (SIM 337.2 ± 0.5 Da). Figure 8B is a positive DART API PE (1.0 mm outlet tip) mass chromatogram of cocaine (SIM 304.3 ± 0.5 Da). Figure 8C is a positive DART API PE (1.0 mm outlet tip) mass chromatogram of codeine (SIM 300.3 ± 0.5 Da). Figure 8D is a positive DART API PE (1.0 mm outlet tip) TIC trace of the formed ions. In one embodiment of the present invention, the amount of sample desorbed is increased by completing the movement of the sample to a predetermined position, increasing the pressure applied to the carrier gas at short intervals, and then turning off the carrier gas pressure. Without wishing to be bound by theory, it is believed that when a pulse of carrier gas is applied, the ionized species increase. Comparing the peak widths of the mass chromatograms in Figures 8A - 8C with the peak width of the TIC (Figure 8D), it can be seen that there are no background-related ions only for a short period before and after the gas pressure drops. There is almost no continuous period during which ions unrelated to the sample are generated prior to the sample analysis period, and the generation of ions is temporally limited by reducing the flow of ionized species, effectively reducing the generation of background species and sample-related ions. Examining the peak shapes of the mass chromatograms in Figures 8A - 8C and the TIC (Figure 8D), it is shown that the ion generation related to the sample increases rapidly, and when the pulsed gas method is used with a fixed sample, the potential decreases for the tailing of each peak. The absence of background species, as indicated by the line returning to the baseline of the TIC in Figure 8D, enables the use of a less complex peak detection algorithm that has previously been difficult to perform due to the non-uniform peak shape signal.

[0092] Example 6 Using a Mosquito robot, the same sample as in Example 1 was deposited on the sixth QuickStrip.

[0093] Next, the 6th QuickStrip was analyzed using the DART API source operated in the same manner as in Example 5, but the outlet cap was 2.5 mm.

[0094] Figure 9A is the DART API PE (2.5 mm outlet cap) mass chromatogram of fentanyl (SIM 337.2 ± 0.5 Da). Figure 9B is the positive DART API PE (2.5 mm outlet cap) mass chromatogram of cocaine (SIM 304.3 ± 0.5 Da). Figure 9C is the positive DART API PE (2.5 mm outlet cap) mass chromatogram of codeine (SIM 300.3 ± 0.5 Da). Figure 9D is the positive DART API PE (2.5 mm outlet cap) TIC trace of the formed ions. Comparing the TIC obtained using the 1.0 mm outlet cap (Figure 8D) with the TIC obtained using the 2.5 mm outlet cap (Figure 9D), the ionization region is increased by the 2.5 mm outlet cap (compared to the 1.0 mm outlet cap), while the generation of background species did not increase with DART API PE (2.5 mm outlet cap) compared to DART API PE (1.0 mm outlet cap). In an embodiment of the present invention, the absence of ions before increasing the pressure to flow the ionized species through the mesh resulted in the preferential generation of ions related to the sample. After moving the sample to a predetermined position, when introducing the carrier gas for a short time while increasing the pressure, ions related to the sample were preferentially generated. The peak widths from the mass chromatograms (Figures 9A, 9B, 9C) of DART API PE (2.5 mm outlet cap) are narrow and equivalent to those observed with DART API PE (1.0 mm outlet cap) (Figures 8A, 8B, 8C). The reduction in peak tailing is significant, and an improvement in peak abundance is observed, which is different from the observations from continuous and pulsed sample movement experiments where it was observed that the 2.5 mm outlet cap results in a more continuous generation of background species.

[0095] In one embodiment of the present invention, the narrow and abundant peaks observed in the mass chromatograms (Figs. 9A, 9B, 9C) facilitate peak analysis because peak detection is not required. For the narrow and abundant peaks observed in the mass chromatograms (Figs. 9A, 9B, 9C), background subtraction is not necessary to generate a digital representation of the information contained in the mass chromatogram. In the mass chromatograms (Figs. 9A, 9B, 9C), it is possible to sum the abundances of the ion currents over time and generate an average value regardless of the peak height. In this way, it is possible to generate a digital representation of the information contained in the mass chromatograms (Figs. 9A, 9B, 9C). In this way, it is possible to analyze the DART API PE (2.5 mm outlet cap) of 384 samples using 2 seconds of pulsed ionization (t1) and 1 second of jump and delay (t2), which requires 3.4 seconds per sample for peaks resolved at the baseline and a total of 22 minutes for 384 samples. The information contained in the 384 mass chromatograms can be saved in a single file and accessed using analysis software. In one embodiment of the present invention, analysis software can be used to determine both the quantitative and qualitative information of 384 samples saved in a single file. In one embodiment of the present invention, by generating a mass chromatogram containing peaks that do not require operations such as peak detection or background subtraction and combining the analysis with saving to a single file, the speed of opening the saved file and saving the information is not restricted by the sampling speed.

[0096] In an embodiment of the present invention, the sample includes two or more sample spots, the first sample spot is separated from the second sample spot by a distance d, and the two or more sample spots are operated as follows. One or more ionized species are directed towards the first sample spot during the time t1 of the first pulse of two or more pulses, and one or more ionized species are directed towards the second sample spot during the time t1 of the second pulse of two or more pulses, where the two or more pulses are separated by a time t2, and the peak abundance corresponding to one or more samples detected by a spectrometer for the first sample spot is detected between a lower limit of about 0.9t1 seconds and an upper limit of about 1.1t1 seconds and was about plus or minus 10% on average with respect to the peak abundance. In an alternative embodiment of the present invention, the peak abundance corresponding to one or more sample ions detected by a spectrometer for the first sample spot is detected between a lower limit of about 0.95t1 seconds and an upper limit of about 1.05t1 seconds. In one embodiment of the present invention, the relative peak abundance corresponding to background ions compared to the peak abundance corresponding to sample ions detected by a spectrometer for a sample spot is between a lower limit of about 0.01 and an upper limit of about 0.1.

[0097] Example 7 The gas pulse is completed by lowering the gas pressure proximal to the outlet cap (Figure 2(119)), then raising it, to establish the gas flow to the mesh. The greater the flow of the carrier gas, the greater the movement of ionized species towards the mesh. To examine the effect of the carrier gas flow (e.g., carrier gas volume) on the generation of target ions from the sample, the same volume of sample was exposed to ionized species exiting a 1.0 mm outlet cap versus those exiting a 2.5 mm outlet cap, and with equal pressure proximal to the hole, the volume of gas flowing through the outlet orifice is greater for the 2.5 mm outlet cap. Using the comparison of SIM of analyte fentanyl in a 200 nL sample, the comparison of the relative abundance of protonated molecules for gas exiting a 1.0 mm outlet cap (Figure 4A) versus a 2.5 mm outlet cap (Figure 5A) is dramatic in the following respects. As more ionized species are directed towards the sample on the mesh, the relative abundance decreases dramatically. Similar results are observed for cocaine (Figure 4B) versus (Figure 5B), and codeine (Figure 4C) versus (Figure 5C). Examining the relative abundance of all ions generated in each analysis, the TIC generated using a 1.00 outlet cap (Figure 4D) versus a 2.5 mm outlet cap (Figure 5D) shows the following. While the relative abundance of the 1.0 mm outlet cap appears significant with respect to the 2.5 mm outlet cap, the generation of a significantly larger volume of ions that reduces the generation of analyte ions of interest is due to the almost continuous generation and detection of ions when using the 2.5 mm outlet cap. The continuum of ions generated in the 2.5 mm outlet cap experiment represents the generated background species, and it is observed that these ions reduce the volume of ionized species available for the generation of detectable analytes.

[0098] The experiments described in Examples 5 - 7 show the influence of background species on detection without pulse ionization and sample movement. The examination of the influence of the exit cap on ion generation in DART API HE is performed by examining the SIM of the analyte fentanyl in a 200 nL sample. Comparing the relative abundances of protonated molecules for a 1.0 mm exit cap (Figure 6A) versus a 2.5 mm exit cap (Figure 7A), the following is found. The effect of the exit cap is not as pronounced as the difference between DART API HE and DART API CIE. The relative abundance of fentanyl - related ions is higher for DART API CIE with a 1.0 mm exit cap (see Figure 5A). Similar results are observed for cocaine (Figure 6B) versus (Figure 7B), and codeine (Figure 6C) versus (Figure 7C). Examining the relative abundances of all ions generated in each analysis, the TICs generated using a 1.0 mm exit cap (Figure 6D) versus a 2.5 mm exit cap (Figure 7D) are more similar in the case of DART API PE. This is because the relative abundances of the ions are more equivalent despite the greater gas flow to the mesh. In the case of DART API HE, an improvement in ion generation from the analyte is seen, but the 2.5 mm exit cap still appears to induce ionization of background substances and is thus not ideal.

[0099] By the experiments described in Examples 5 to 7, the influence of the background on the detection using DART API HE was identified. Under the experimental conditions of DART API PE, the period during which the generated mass spectrum is rich in sample-related ions is short, and the spot where the sample is applied to the mesh is no longer in the region affected by the ionized species, so the sample-related ions decrease. In one embodiment of the present invention, the examination of the effect of the exit cap on ion generation in DART API PE is performed by the examination of SIM for the analyte fentanyl in a 200 nL sample. The comparison of the relative abundance of the protonated molecule in the case of the gas exiting the 1.0 mm exit cap (Figure 8A) versus the 2.5 mm exit cap (Figure 9A) is significantly improved in the case of the 2.5 mm exit cap, and the relative abundance and the dramatic increase and decrease of fentanyl SIM are improved compared to the 1.0 mm exit cap. Similar results are observed for cocaine (Figure 8B) versus (Figure 9B), and codeine (Figure 8C) versus (Figure 9C). Examining the relative abundance of all the ions generated in each analysis, it can be seen that in DART API PE, the 2.5 mm exit cap improves the detection of the analyte. The TIC generated using the 1.0 mm exit cap (Figure 8D) shows the generation of a smaller amount of ions than that generated by the 2.5 mm exit cap (Figure 9D), but since it is most desirable to generate analyte ions rather than background species, DART API PE with a 2.5 mm exit cap is preferred.

[0100] In one embodiment of the present invention, it has been observed that the DART API PE produces more uniform peaks, indicating less interference from background species. In one embodiment of the present invention, the DART API PE and DART API HE reduce the likelihood that the sample is completely removed from the target during analysis and limit the possibility of ionization of background species. In embodiments of the present invention, a sufficient gas flow for both desorption and ionization of the sample is achieved by matching the pressure and flow of the device to the pulse duration and optimally desorbing the sample over that duration. The observation of improved signals with different exit caps is important in that the sample size may vary and thus it may be necessary to ionize from a larger surface area. Flowing more ionized species through the 2.5 mm exit cap results in a wider ionization field, as shown for DART API CIE (see FIGS. 4 and 5) and DART API HE where the TIC did not return to baseline. A wider ionization field may result in improved results when the sample is applied with lower positional accuracy or when the sample is dispersed over a wider area. However, with accurate positioning accuracy and application of a small amount of sample, a wider ionization field is not necessary. On the other hand, an insufficient flow of carrier gas is also a condition that should probably be avoided. That is, sufficient ionized species are required to ionize the sample properly.

[0101] A common premise when analyzing a sample is that the more sample present, the greater the signal intensity observed for that sample. Further, from that premise, it follows that the amount of sample ions desorbed can be increased by moving the sample through the ionized species as a function of time such that all of the sample is desorbed. Unexpectedly, based on the results presented, the basis of both of these premise conditions may be called into question. As an unexpected result, an improvement in sensitivity can be observed by (i) accurately placing a sample of reduced volume and (ii) accurately placing a short pulse of ionized species on the sample without moving the position of the ionized species relative to the sample. Embodiments contemplated in this specification further include the following embodiments R1 - R35, S1, and T1 - T50.

[0102] Embodiment R1. A sampler for depositing a large amount of biological sample for atmospheric ionization, comprising a mesh designed to limit the area of the sample, a supply unit capable of directing ionized species formed in the atmosphere towards the sample in a restricted area, and a spectrometer for analyzing sample ions formed by the ionized species.

[0103] Embodiment R2. The sampler of Embodiment R1, wherein the sample is one or more of adsorbed, absorbed, bound, and contained on the mesh.

[0104] Embodiment R3. The sampler of Embodiment R1 or R2, further comprising means for arranging the mesh to interact with the ionized species.

[0105] Embodiment R4. The sampler of any one of Embodiments R1 - R3, wherein the diluted sample density on the surface is between about 1 picogram per square millimeter and about 1 nanogram per square millimeter.

[0106] Embodiment R5. The sampler of any one of Embodiments R1 - R4, wherein the ionized species include ionized species dispersed in a gas.

[0107] Embodiment R6. The sampler of any one of Embodiments R1 - R5, further comprising a gas ion separator introduced after the ionized species interact with the diluted sample and before the sample ions enter the spectrometer.

[0108] Embodiment R7. The sampler of any one of Embodiments R1 - R6, wherein the mesh is a grid.

[0109] Embodiment R8. The sampler of any one of Embodiments R1 - R7, further comprising means for moving the mesh with respect to the ionized species.

[0110] Embodiment R9. An ionization device for pulse atmospheric pressure ionization of a sample present in serum, comprising a surface designed to limit the surface area, and a robot programmed to receive the sample, programmed to generate a restricted area sample, and programmed to deliver the sample to the restricted area surface, wherein the sample density on the surface is less than about 1 nanogram per square millimeter, and a supply unit capable of directing ionization species formed from a pulse atmospheric ionization source at the sample in the restricted area of the surface.

[0111] Embodiment R10. The ionization device according to Embodiment R9, wherein the diluted sample is one or more of adsorbed, absorbed, bound, and contained on the surface.

[0112] Embodiment R11. The ionization device according to Embodiment R9 or R10, further comprising means for arranging the surface to interact with the ionization species.

[0113] Embodiment R12. The ionization device according to any one of Embodiments R9 to R11, wherein the ionization species include ionization species dispersed in a gas.

[0114] Embodiment R13. The ionization device according to any one of Embodiments R9 to R12, further comprising a gas ion separator.

[0115] Embodiment R14. The ionization device according to any one of Embodiments R9 to R13, wherein the surface is a grid.

[0116] Embodiment R15. The ionization device according to any one of Embodiments R9 to R14, further comprising means for moving the surface relative to the ionization species.

[0117] Embodiment R16. The ionization device according to any one of Embodiments R9 to R15, wherein the surface supports a plurality of samples, and the plurality of samples are separated by a distance sufficient to prevent the ionization species from simultaneously desorbing sample material from adjacent samples.

[0118] Embodiment R17. An ionization device according to any one of Embodiments R9 to R16, wherein the surface is attached to a movable stage, and the stage speed is controlled to move the sample through the ionizing species at a speed such that the ionizing species do not simultaneously desorb sample material from an adjacent sample.

[0119] Embodiment R18. An ionization device according to any one of Embodiments R9 to R17, wherein the speed of the surface is sufficient for the sample to completely vaporize independently of an adjacent sample.

[0120] Embodiment R19. An ionization device according to any one of Embodiments R9 to R18, wherein the speed of the surface is sufficient to increase the sample density on the surface per square millimeter.

[0121] Embodiment R20. A method of ionizing a sample, the method comprising receiving the sample, diluting the sample with water, applying the diluted sample to a grid, and passing the sample over the grid in front of a pulsed atmospheric pressure ionization source.

[0122] Embodiment R21. The method of Embodiment R20, wherein the sample passes in front of the atmospheric pressure ionization source at an adjusted speed.

[0123] Embodiment R22. The method of Embodiment R20 or R21, wherein the adjusted speed is increased to reduce the matrix effect.

[0124] Embodiment R23. A method according to any one of Embodiments R20 to R22, wherein the flow of ionizing species exiting the pulsed atmospheric pressure ionization source is discontinuous.

[0125] Embodiment R24. A method according to any one of Embodiments R20 to R23, wherein the flow of ionizing species exiting the pulsed atmospheric pressure ionization source is initiated when the sample has moved to a position in front of the ionization source outlet to complete the analysis of the sample.

[0126] Embodiment R25. A method according to any one of Embodiments R20 to R24, in which the flow of ionized species exiting the pulsed atmospheric pressure ionization source and the inflow of the sample to a position proximal to the flow coincide in time.

[0127] Embodiment R26. A method according to Embodiment R25, in which the coinciding period is temporally limited by incomplete desorption of the sample.

[0128] Embodiment R27. A method according to Embodiment R26, in which incomplete desorption results in a more Gaussian distribution of the ionized sample.

[0129] Embodiment R28. A method according to Embodiment R27, in which the Gaussian distribution of sample-related ions enables collection of more uniform data packets.

[0130] Embodiment R29. A method according to Embodiment R28, in which a uniform packet of data can be processed using a statistical analysis program without the need for background subtraction of data that would normally be collected when the sample present on the grid is completely desorbed.

[0131] Embodiment R30. A method according to Embodiment R29, in which the results of statistical analysis are improved by using more uniform packets of data.

[0132] Embodiment R31. A method according to Embodiment R30, in which the flow of ionized species exiting the pulsed atmospheric pressure ionization source is discontinuous and the volume of gas required for analysis can be reduced.

[0133] Embodiment R32. A method according to Embodiment R31, in which the volume of carrier gas required for desorption and ionization of the sample in a DART experiment is reduced by more than 95 percent.

[0134] Embodiment R33. A method according to Embodiment R32, in which the use of carrier gas pulses eliminates the generation of ions unrelated to the sample presented on the grid.

[0135] Embodiment R34. The method of Embodiment R33 that enables selective ionization of different substances present in a sample by combining the use of a carrier gas pulse for generating ionized species with a pulse of a second gas carrier gas and reacting the ionized sample with a second gas generally called a dopant.

[0136] Embodiment R35. An atmospheric pressure ionization device comprising a mesh adapted to contact a sample, a carrier gas supply adapted to generate a pulsed carrier gas, a first atmospheric pressure chamber having an inlet for the pulsed carrier gas, a first electrode therein, and a counter electrode that generates a discharge in the pulsed carrier gas and generates at least metastable neutral excited state species, an outlet port for directing ionized species formed in air towards the mesh, and a spectrometer for analyzing sample ions formed by the ionized species interacting with the sample on the mesh.

[0137] Embodiment S1. A pulsating flow atmospheric pressure ionization device for ionizing a sample, comprising a first atmospheric pressure chamber including an inlet for a carrier gas, a first electrode, a counter electrode, and an outlet port, a power source configured to energize the first electrode and the counter electrode to provide a current between the first electrode and the counter electrode and generate a discharge, and a pressure regulator configured to introduce two or more pulses of the carrier gas into the first atmospheric pressure chamber, wherein the two or more pulses are separated by a time t, the power source operates continuously during the time t, and when each of the two or more pulses of the carrier gas interacts with the discharge, one or more ionized species are generated, and gas contact between the one or more ionized species and the pulsed carrier gas directs the one or more ionized species formed in air towards the sample through the outlet port, thereby forming ions of the sample.

[0138] Embodiment T1. A pulsed flow atmospheric pressure ionization device for ionizing a sample, comprising a first atmospheric pressure chamber including an inlet for a carrier gas, a first electrode, a counter electrode, and an outlet port; a power supply configured to energize the first electrode and the counter electrode to provide a current between the first electrode and the counter electrode and generate a discharge; and a pressure regulator configured to introduce two or more pulses of the carrier gas into the first atmospheric pressure chamber, wherein the duration of the two or more pulses of the carrier gas is during a time t1, the two or more pulses of the carrier gas are separated by a time t2, the interaction between the two or more pulses of the carrier gas and the discharge during the time t1 generates one or more ionized species, and the gas contact between the one or more ionized species and the two or more pulses of the carrier gas directs the one or more ionized species formed in the atmosphere toward the sample through the outlet port, thereby forming ions of the sample.

[0139] Embodiment T2. The sampler according to Embodiment T1, wherein the power supply is configured to continuously energize the first electrode and the counter electrode.

[0140] Embodiment T3. The sampler according to Embodiment T1 or T2, wherein the one or more ionized species include ions, electrons, hot atoms, hot molecules, radicals, and metastable neutral excited state species.

[0141] Embodiment T4. The sampler according to any one of Embodiments T1 to T3, wherein the sample includes an analyte applied to a mesh, a dip-in probe, an SPME fiber, a wand with a ticket, a glass or metal slide, a filament, a glass or metal rod, a fiber, or a wire loop.

[0142] Embodiment T5. The sampler according to any one of Embodiments T1 to T4, further including a cap on the outlet port, the cap having an outlet hole between a lower limit of about 0.1 mm and an upper limit of about 4 mm.

[0143] Embodiment T6. The sample includes two or more sample spots, the first sample spot is separated from the second sample spot by a distance d, and for the two or more sample spots, one or more ionized species are directed towards the first sample spot during the time t1 of the first pulse among two or more pulses of the carrier gas, and one or more ionized species are directed towards the second sample spot during the time t1 of the second pulse among two or more pulses of the carrier gas, and the sampler of any one of Embodiments T1 - T5 is operated as such.

[0144] Embodiment T7. The two or more sample spots are operated such that the two or more sample spots remain stationary during the time t1, and the sampler is of Embodiment T6.

[0145] Embodiment T8. The two or more sample spots are operated during the time t2 such that one or more ionized species are directed from the first sample spot towards the second sample spot, and the sampler is of Embodiment T6 or T7.

[0146] Embodiment T9. The two or more sample spots are operated such that the two or more sample spots are moved over the distance d during the time t2, and the sampler is of any one of Embodiments T6 - T8.

[0147] Embodiment T10. For the sampler of Embodiment T9, the distance d is between a lower limit of about 0.5 mm and an upper limit of about 9 mm.

[0148] Embodiment T11. The sampler of any one of Embodiments T1 - T6 further includes a cap on an outlet port having an outlet hole, and the dimensions of the outlet hole are selected to generate a spatial resolution between a lower limit of about 0.2 mm and an upper limit of about 9 mm.

[0149] Embodiment T12. The sample includes two or more sample spots, the first sample spot is separated from the second sample spot by a distance d, and for the sampler of Embodiment T11, the spatial resolution is selected based on the distance d.

[0150] Embodiment T13. A sampler according to any one of Embodiments T1 to T12, wherein the generated discharge is one or more of a corona discharge, an arc discharge, and a glow discharge.

[0151] Embodiment T14. A sampler according to any one of Embodiments T1 to T13, wherein the time t1 is between a lower limit of about 0.1 second and an upper limit of about 10 seconds.

[0152] Embodiment T15. A sampler according to any one of Embodiments T1 to T14, wherein the time t2 is between a lower limit of about 0.1 second and an upper limit of about 10 seconds.

[0153] Embodiment T16. A sampler according to any one of Embodiments T1 to T15, further comprising a heating element in fluid communication with the first atmospheric pressure chamber.

[0154] Embodiment T17. The sampler of Embodiment T16, wherein the carrier gas passes near the heating element.

[0155] Embodiment T18. The sampler of Embodiment T16 or T17, wherein the carrier gas is heated to a temperature between a lower limit of about 100°C and an upper limit of about 500°C.

[0156] Embodiment T19. A sampler according to any one of Embodiments T1 to T18, further comprising a grid disposed at the outlet port.

[0157] Embodiment T20. The sampler of Embodiment T19, wherein a first potential is applied to the grid to deflect charged species.

[0158] Embodiment T21. A sampler according to any one of Embodiments T1 to T20, wherein the carrier gas pressure is between a lower limit of about 0 psi and an upper limit of about 80 psi.

[0159] Embodiment T22. A device for analyzing a sample, comprising a first atmospheric pressure chamber including an inlet for a carrier gas, a first electrode, a counter electrode, and an outlet port; a power supply configured to energize the first electrode and the counter electrode to provide a current between the first electrode and the counter electrode to generate a discharge; and a pressure regulator configured to introduce the carrier gas into the first atmospheric pressure chamber and generate two or more pulses of the carrier gas. The duration of the two or more pulses of the carrier gas is during a time t1, the two or more pulses of the carrier gas are separated by a time t2, the interaction between the two or more pulses of the carrier gas and the discharge during the time t1 generates one or more ionized species, and the gas contact between the one or more ionized species and the two or more pulses of the carrier gas directs one or more ionized species formed in the atmosphere toward the sample through the outlet port to generate one or more sample ions, and the device includes a spectrometer for analyzing the one or more sample ions.

[0160] Embodiment T23. The device of Embodiment T22, wherein the power supply is configured to continuously energize the first electrode and the counter electrode.

[0161] Embodiment T24. The device of Embodiment T22 or T23, wherein the one or more ionized species include ions, electrons, hot atoms, hot molecules, radicals, and metastable neutral excited state species.

[0162] Embodiment T25. The device of any one of Embodiments T22 to T24, wherein the sample is an analyte applied to a mesh, a dip-it probe, an SPME fiber, a wand with a ticket, a glass or metal slide, a filament, a glass or metal rod, a fiber, or a wire loop.

[0163] Embodiment T26. The device of any one of Embodiments T22 to T25, further comprising a gas ion separator.

[0164] Embodiment T27. A device according to any one of Embodiments T22 to T26, wherein the gas ion separator increases the peak abundance of one or more sample ions compared to low-mass ions.

[0165] Embodiment T28. A device for analyzing a sample, comprising: a first atmospheric pressure chamber including an inlet for a carrier gas, a first electrode, a counter electrode, and an outlet port; a power supply configured to energize the first electrode and the counter electrode to provide a current between the first electrode and the counter electrode to generate a discharge; and a pressure regulator configured to introduce the carrier gas into the first atmospheric pressure chamber and generate two or more pulses of the carrier gas, wherein the duration of the two or more pulses of the carrier gas is during a time t1, the two or more pulses of the carrier gas are separated by a time t2, the interaction between the two or more pulses of the carrier gas and the discharge during the time t1 generates one or more ionized species, and the gas contact between the one or more ionized species and the two or more pulses of the carrier gas directs one or more ionized species formed in the atmosphere toward the sample through the outlet port to generate one or more sample ions, and further comprising a spectrometer for generating a mass chromatogram from the analysis of the one or more sample ions.

[0166] Embodiment T29. The device of Embodiment T28, wherein the power supply is configured to continuously energize the first electrode and the counter electrode.

[0167] Embodiment T30. The device of Embodiment T28 or T29, wherein the one or more ionized species include ions, electrons, hot atoms, hot molecules, radicals, and metastable neutral excited state species.

[0168] Embodiment T31. The device according to any one of Embodiments T28 to T30, wherein the sample is an analyte applied to a mesh, a dip-it probe, an SPME fiber, a wand with a ticket, a glass or metal slide, a filament, a glass or metal rod, a fiber, or a wire loop.

[0169] Embodiment T32. A device according to any one of Embodiments T28 to T31, wherein the sample includes two or more sample spots, the first sample spot is separated from the second sample spot by a distance d, and the two or more sample spots are such that one or more ionized species are directed at the first sample spot during a time t1 of a first pulse of two or more pulses of a carrier gas, and one or more ionized species are directed at the second sample spot during a time t1 of a second pulse of the two or more pulses of the carrier gas.

[0170] Embodiment T33. A device according to any one of Embodiments T28 to T32, wherein the two or more sample spots are operated such that the two or more sample spots remain stationary during the time t1.

[0171] Embodiment T34. A device according to any one of Embodiments T28 to T33, wherein the two or more sample spots are operated such that one or more ionized species are directed from the first sample spot to the second sample spot during the time t2.

[0172] Embodiment T35. A device according to any one of Embodiments T28 to T34, further including a gas ion separator.

[0173] Embodiment T36. The device of Embodiment T35, wherein the gas ion separator increases the peak abundance of one or more sample ions compared to low-mass ions.

[0174] Embodiment T37. A device according to any one of Embodiments T28 to T36, wherein background ions are not detected during the time t2.

[0175] Embodiment T38. A device according to any one of Embodiments T28 to T37, wherein the relative peak abundance corresponding to background ions compared to the peak abundance corresponding to one or more sample ions detected by a spectrometer for the first sample spot is between a lower limit of about 0.01 and an upper limit of about 0.1.

[0176] Embodiment T39. A device according to any one of Embodiments T28 to T38, wherein one or more sample ions detected by a spectrometer are detected during a time t1.

[0177] Embodiment T40. A device according to any one of Embodiments T28 to T39, wherein one or more sample ions detected by a spectrometer corresponding to a first sample spot are detected during a time t1.

[0178] Embodiment T41. A device according to any one of Embodiments T28 to T40, wherein the abundance of a peak corresponding to one or more sample ions detected by a spectrometer for a first sample spot is detected between a lower limit of about 0.9×t1 seconds and an upper limit of about 1.1×t1 seconds.

[0179] Embodiment T42. A device according to any one of Embodiments T28 to T41, wherein one or more peaks of a mass chromatogram do not require peak detection.

[0180] Embodiment T43. A device according to any one of Embodiments T28 to T42, wherein the peak abundance during a time t1 eliminates the need for peak detection.

[0181] Embodiment T44. A device according to any one of Embodiments T28 to T43, wherein mass chromatograms for a plurality of samples are stored in one data file.

[0182] Embodiment T45. A method for ionizing an analyte using a flapping flow atmospheric pressure ionization device, comprising: (a) energizing a first electrode with respect to a second electrode disposed at an interval from the first electrode, wherein the first electrode and the second electrode are disposed in a chamber, the chamber includes a gas inlet and an outlet, and energizing the first electrode with respect to the second electrode generates a discharge; (b) introducing two or more pulses of a carrier gas into the chamber through the gas inlet, wherein the duration of the two or more pulses of the carrier gas is t1, and the two or more pulses of the carrier gas are separated by a time t2; (c) generating ions, electrons, and excited state species of the two or more pulses of the carrier gas; and (d) directing the ions, electrons, and excited state species toward the analyte.

[0183] Embodiment T46. The method of Embodiment T45, wherein the second electrode is continuously energized with respect to the first electrode during the time t1 + t2.

[0184] Embodiment T47. The analyte includes a first sample spot and a second sample spot, the first sample spot is separated from the second sample spot by a distance d, and further comprising (e) operating the first sample spot and the second sample spot such that the ions, electrons, and excited state species are directed toward the first sample spot during the first pulse of the two or more pulses of the carrier gas, and the ions, electrons, and excited state species are directed toward the second sample spot during the second pulse of the two or more pulses of the carrier gas. The method according to Embodiment T45 or T46.

[0185] Embodiment T48. The method of Embodiment T47, further comprising (f) holding the first sample spot in a stationary state during a first duration t1.

[0186] Embodiment T49. The method of Embodiment T48, further comprising (g) holding the second sample spot in a stationary state during a second duration t1.

[0187] Embodiment T50. (h) The method of Embodiment T49, further comprising moving from the first sample spot to the second sample spot during time t2.

[0188] Exemplary embodiments of the methods, systems, and components of the present invention are described herein. As noted elsewhere, these exemplary embodiments are described for illustrative purposes only and are not limiting. Other embodiments are possible and are covered by the present invention. Such embodiments will be apparent to those of ordinary skill in the relevant art based on the teachings contained herein. For example, it is envisioned that, regardless of the actual shapes shown in the various figures and embodiments above, the outer diameter of the inlet tube at the outlet can be tapered or non-tapered, and the outer diameter of the outlet tube at the inlet can be tapered or non-tapered.

[0189] Accordingly, the breadth and scope of the present invention should not be limited by any of the above-described exemplary embodiments, but should be defined only in accordance with the following claims and their equivalents.

Claims

1. An ionization device for pulsed atmospheric ionization of a sample, comprising: A first atmospheric pressure chamber, comprising: An inlet for a carrier gas, A first electrode, A counter electrode, and An outlet port; a first atmospheric pressure chamber including the same; A power source configured to energize the first electrode and the counter electrode to supply a current between the first electrode and the counter electrode to generate a discharge; A pulse generator configured to pulse the carrier gas into the first atmospheric pressure chamber to generate two or more pulses of the carrier gas that form ions of the sample.

2. The duration of each pulse from two or more pulses of the carrier gas is the time t １ The ionization device according to claim 1, wherein the ionization device is as described above.

3. Two or more pulses of the carrier gas are separated by a time t ２ and one or more ionized species are generated during each time t by the interaction with the discharge. The ionization device according to claim 1 or 2 １ ​

4. The ionization device according to claim 3, wherein gas contact between the one or more ionization species and the two or more pulses of the carrier gas directs the one or more ionization species formed in the atmosphere toward the sample through the outlet port.

5. The ionization device according to any one of claims 3 to 4, wherein the one or more ionization species include ions, electrons, hot atoms, hot molecules, radicals, and metastable neutral excited state species.

6. The sample includes two or more sample spots, a first sample spot is separated from a second sample spot by a distance d, and the two or more sample spots are such that the one or more ionized species are directed at the first sample spot during a duration t １ of a first pulse among two or more pulses of the carrier gas, and the one or more ionized species are directed at the second sample spot during a duration t １ of a second pulse among two or more pulses of the carrier gas, and is operated as such. The ionization device according to any one of claims 3 to 5

7. The two or more sample spots are operated such that the two or more sample spots remain stationary during the time t １ The ionization device according to claim 6, wherein the two or more sample spots are operated such that the two or more sample spots remain stationary during the time t

8. The two or more sample spots are at the time t ２ The ionization device according to claim 6, wherein during, the one or more ionized species are operated to be directed from the first sample spot to the second sample spot.

9. The ionization device according to any one of claims 2 to 8, wherein the power source is configured to continuously energize the first electrode and the counter electrode.

10. The ionization device according to any one of claims 2 to 9, wherein the sample includes an analyte applied to a mesh, a dip-in probe, an SPME fiber, a wand with a ticket, a glass or metal slide, a filament, a glass or metal rod, a fiber, or a wire loop.

11. The ionization device according to any one of claims 2 to 10, further including a cap on the outlet port, the cap having an outlet hole between a lower limit of 0.1 mm and an upper limit of 4 mm.

12.

13.

14. A device for ionizing a sample, comprising: A first atmospheric pressure chamber, comprising: An inlet for a carrier gas, A first electrode, A counter electrode, and An outlet port; a first atmospheric pressure chamber including the same; A power source configured to energize the first electrode and the counter electrode to supply a current between the first electrode and the counter electrode to generate a discharge; A pulse generator configured to introduce a carrier gas into the first atmospheric pressure chamber to generate two or more pulses of the carrier gas, wherein the duration of each pulse from the two or more pulses of the carrier gas is time t １ and the two or more pulses of the carrier gas are separated by time t ２ and the interaction between the two or more pulses of the carrier gas and the discharge during the time t １ generates one or more ionized species during each time t １ and the gas contact between the one or more ionized species and the two or more pulses of the carrier gas directs the one or more ionized species formed in the atmosphere towards the sample through the outlet port, thereby generating one or more sample ions, a pulse generator, and an apparatus including the same.

13. The device according to claim 12, wherein the power source is configured to continuously energize the first electrode and the counter electrode.

14. A method of ionizing an analyte using an atmospheric pressure ionization device, comprising: (a) energizing the first electrode with respect to a second electrode disposed at a distance from the first electrode, wherein the first electrode and the second electrode are disposed in a chamber, the chamber includes a gas inlet and an outlet, and energizing the first electrode with respect to the second electrode generates a discharge; (b) introducing two or more pulses of carrier gas into the chamber through the gas inlet, wherein the duration of each pulse from the two or more pulses of carrier gas is time t １ and the two or more pulses of carrier gas are separated by time t ２ and introducing them (c) generating ions, electrons, and excited state species of two or more pulses of the carrier gas; and (d) directing the ions, electrons, and excited state species towards the analyte.

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