Dynamic spray mass spectrometry

Abstract

Disclosed herein are systems and methods for ionizing compounds. In some implementations, the systems and methods include a first voltage and second voltage, applied in a continuous voltage sweep from a voltage of less than 2 kV to a voltage of greater than 4 kV.

Description

DYNAMIC SPRAY MASS SPECTROMETRYSTATEMENT OF GOVERNMENT SUPPORT

[0001] This invention was made with government support under grant / contract number CHE-2305057, awarded by the National Science Foundation, and DE-SC0022097, awarded by the United States Department of Energy. The government has certain rights in the invention.CROSS-REFERENCE TO RELATED APPLICATION

[0002] This application claims the benefit of U.S. Provisional Application 63 / 656,829, filed June 6, 2024, the contents of which are hereby incorporated in its entirety.BACKGROUND

[0003] Mass spectrometry is an analytical technique characterized by its excellent sensitivity, robust selectivity, and rapid response. The four stages of mass spectrometry are ionization, acceleration, separation, and detection. Amongst that, the ionization step is a crucial factor in mass spectrometry analysis of complex mixtures as it modulates the metabolic coverage and limit of detection. Existing ionization techniques remain incapable of ionizing samples with diverse physicochemical properties (polar / non-polar, basic / acidic, and high / low molecular weight molecules) using a single ionization source. Electrospray ionization (ESI) and atmospheric pressure chemical ionization (APCI) are the two most common ionization mechanisms involved in complex mixture analysis. Electrospray ionization (ESI) suits thermally labile, nonvolatile, and polar compounds over a wide mass range, while atmospheric pressure chemical ionization (APCI) is ideal for nonpolar or less polar compounds with lower molecular weights. Combining ESI and APCI capabilities expands detection ranges for polarity and mass, providing complementary information on sample composition.

[0004] Various ESI / APCI hybrid ionization sources have been developed to date. However, the two independent ion sources are operated separately, which typically require laborious manual voltage optimizations for switching between ESI and APCI ionization modes. Complex switching of voltages is required because different analytes ionize at different voltages, which makes it challenging for some compounds to get detected in complex mixtures / biofluids.

[0005] There remains a need for improved systems and methods for the sequential ionization of various molecules under ambient conditions without sample pretreatments from small to large volume samples.BRIEF DESCRIPTION OF THE FIGURES

[0006] Figure 1 depicts a representation of dynamic nESI-MS.

[0007] Figure 2 depicts analysis conducted using Dynamic nESI-MS: (A) Total ion chronogram obtained from the analysis of 250 mM vitamin D2 in MeOH. (B) Acquired mass spectrum of vitamin D2 at dynamic droplet / plasma conditions (6 kV DC) along with extracted ion chronogram of (C) M+* (m / z 397) ion species under 75 s ramping times. (D) Mass spectrum acquired at nESI conditions (absence of vitamin D2 peak).

[0008] Figure 3 depicts analysis conducted using Dynamic nESI-MS: (A) The total ion chronogram resulting from the analysis of 250 pM cholesterol in ethanol. (B) Mass spectrum of cholesterol acquired under dynamic droplet / plasma conditions (5 kV DC), accompanied by the extracted ion chronogram (C) [M + H - H?O]+(m / z 369) ion species under 8 s ramping times. (D) Mass spectrum obtained under nESI conditions, displaying the absence of a cholesterol peak.

[0009] Figure 4 depicts analysis conducted using Dynamic nESI-MS: (A) Mass spectrum acquired at each constant DC voltage applied to cholesterol sample (250 mM in EtOH) starting from 1 kV to 6 kV. (A) For the first nESI tip, cholesterol [M + H - HzO]+(m / z 369) ion species detected at >4.55 kV. (B) For the sond tip, they are detected at >5 kV.

[0010] Figure 5 depicts analysis conducted using Dynamic nESI-MS: (A) Total ion chronogram derived from the analysis of 100 pM ubiquitin in H2O. (B) The acquired mass spectrum of ubiquitin with several charged states under dynamic droplet / plasma conditions (2 kV DC), coupled with the corresponding extracted ion chronogram (C) [M + 7H]+(m / z 1224) ion species under 8 s ramping times. (D) Mass spectrum obtained under APCI conditions, demonstrating the absence of a ubiquitin peak.

[0011] Figure 6 depicts analysis conducted using Dynamic nESI-MS: (A) Total ion chronogram originating from the evaluation of 100 pM cytochrome c in H2O. (B) Acquired mass spectrum of cytochrome c at dynamic droplet / plasma conditions (2 kV DC) along with extracted ion chronogram of (C) [M + 9H]+(m / z 1529) ion species under 8 s ramping times. (D) Mass spectrum obtained under APCI conditions, indicating the lack of a cytochrome c signal.

[0012] Figure 7 depicts analysis conducted using Dynamic nESI-MS: (A) Total ion chronogram of methanolic cocaine (10 ppm) / vitamin D2 (100 ppm) solution under 8 s ramping time. (B) Mass spectrum of the mixture in ESI mode. (C) Total ion chronogram for 75 s ramping time. (D) Mass spectrum of the mixture in APCI mode.

[0013] Figure 8 depicts analysis conducted using Dynamic nESI-MS: (A) Single ion monitoring chronogram of methanolic vitamin D2 (250 mM) solution under 8 s ramping time. (B) Time to voltage conversion plot for 8 s ramping time.

[0014] Figure 9 depicts analysis conducted using Dynamic nESI-MS: (A) Chronogram for single ion monitoring of a 250 pM vitamin D2 solution in methanol with a 75 s ramping time. (B) Plot illustrating the conversion of time to voltage for a 75 s ramping time.

[0015] Figure 10 depicts analysis conducted using Dynamic nESI-MS: (A) Single ion monitoring chronogram for a 250 pM vitamin D2 solution in methanol, employing a ramping time of 150 s. (B) Plot depicting the conversion of time to voltage for a ramping duration of 150 s.

[0016] Figure 11 depicts analysis conducted using Dynamic nESI-MS: (A) Single ion monitoring chronogram of 250 mM vitamin D2 solution in methanol under 225 s ramping time. (B) Plot showing the transformation of time into voltage for a ramping duration of 225 s.

[0017] Figure 12 depicts analysis conducted using Dynamic nESI-MS: (A) Single ion monitoring of a 250 pM vitamin D2 solution in methanol, utilizing a ramping time of 300 s. (B) Time to voltage conversion plot for 300 s ramping time.

[0018] Figure 13 depicts a system for Dynamic plasma-in-droplet ionization (PIDI) mass spectrometry

[0019] Figure 14 depicts a proposed mechanisms of PIDI process for (A) protonated small molecules and ions (similar to ion evaporation model in ESI), (B) neutral small molecules, and (C) proteins (similar to charge residue model in ESI but with charged solvent protect a protein from APCI discharge).

[0020] Figure 15 depicts PIDI-MS analysis of equimolar mixture (200 pM) of 6 compounds in MeOI-kHzO, 70:30 (5-fluorouracil (1), caffeine (2), 6-estradiol (3), cocaine (4), vitamin D2 (5), and ubiquitin (6)) by (A) ESI mode and (B) PIDI mode. All compounds were detected by PIDI mode while ESI mode was able to detect only cocaine and ubiquitin.

[0021] Figure 16 depicts a calibration curve for cocaine (10 - 1000 pg / mL in MeOH / HjO) in presence of 500 pg / mL cocaine-D3 as IS using PIDI MS2 with MRM (transitions m / z 304 -> 182 and m / z 307 -> 185 for the analyte and IS, respectively). Insert shows the part of calibration curve at lower concentrations (10 - 250 pg / mL).

[0022] Figure 17 depicts a calibration curve of cholesterol (0.4 - 193 pg / mL in EtOH) in presence of 193 pg / mL cholesterol-D7 as IS using PIDI MS. Insert shows the part of calibration curve at lower concentrations (0.4 - 19 pg / mL).

[0023] Figure 18 depicts mass spectra obtained following the analysis of 100 pM ubiquitin in MeOH / HjO at 50 psi Nj by (A) ESI mode (3.5 kV and 5 kV) and (B) PIDI mode (3.5 kV and 5 kV).

[0024] Figure 19 depicts PIDI-MS spectra for 100 pM cytochrome C solution in MeOH / HjO at different spray voltages (3.5 kV, 4 kV, 4.5 kV, 5 kV, 5.5 kV, and 6 kV).

[0025] Figure 20 depicts the dependance of source current (pA) on source voltage (kV) for charged droplets, charged droplets in nonthermal plasma, and plasma. For droplets and plasma in droplets, MeOH was used as an analyte while MeOH headspace vapor was employed for plasma. The experiment was conducted without any nebulizing gas.

[0026] Figure 21 depicts flowrate (pL / min) optimizations for PIDI-MS analysis of 100 ppb cocaine solution in MeOH / HjO under 100 psi of Nj. The highest absolute ion intensity was obtained at 100 pL / min.

[0027] Figure 22 depicts PIDI-MS analysis: (A) Total ion chronogram acquired from the PIDI analysis of 250 mM cholesterol in ethanol. (B) Mass spectrum of cholesterol at dynamic plasma in droplet conditions (5 kV voltage ) along with extracted ion chronogram of (C) [M+H-HjOP (m / z 369) ion species under 8 s ramping times. (D) Mass spectrum obtained at ESI conditions (2 kV voltage) showing the absence of cholesterol peak at m / z 369.

[0028] Figure 23 depicts a system for dynamic flow-through induced paper spray ionization mass spectrometry.

[0029] Figure 24 depicts a calibration curve for cocaine (100 - 1000 pg / mL in MeOH / H2O) in presence of 500 pg / mL cocaine-D3 as IS using FIPSI MS2 with MRM (transitions m / z 304 -> 182 and m / z 307 -> 185 for the analyte and IS, respectively) and MeOH as spray solvent.

[0030] Figure 25 depicts the limit of detection (LOD) data for cocaine in MeOH / HjO, urine, plasma, and blood detected by paper spray ionization (PSI) and flow-through induced paper spray ionization (FIPSI).

[0031] Figure 26 depicts a system for high-throughput dynamic flow-through induced paper spray ionization mass spectrometry.

[0032] Figure 27 depicts a sequential analysis of ubiquitin (1), normorphine (2), [pTyr1146] insulin receptor (3), cocaine (4), and l-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (5) by high-throughput D-FIPSI MS demonstrated by (A) total ion chronogram, (B) extracted ion chronograms of 4 and 5, (C) mass spectrum of 1, and (D) mass spectrum of 5.

[0033] Figure 28 depicts (A) Total ion chronogram of methanolic cocaine (100 mM) / vitamin D2 (500 mM) solution under 8 s ramping time. Mass spectra of the mixture in (B) PSI mode, (C) PSI / APCI and (D) APCI mode.

[0034] Figure 29 depicts (A) Dynamic power supply provides DC voltage with ramping of voltages ranging from 0 to ±8 kV, controlled by maximum DC voltage knob (in kV), minimum DC voltage knob (in % of maximum value), positive / negative polarity switch, ramping on / off switch, and ramping times knob for one polarity (8, 75, 150, 225, and 300 s). (B) Oscilloscope readings showing actual voltage ramping at different times.

[0035] Figure 30 depicts CAD renderings of the custom-designed metal capillary holder used for sputter coating. The holder accommodates up to 60 pulled borosilicate glass capillaries.

[0036] Figure 31 depicts (A) Total ion chronogram acquired from the analysis of 10 pM cocaine and 200 pM cholesterol in ethanol. Mass spectrum of (B) cocaine as [M+H]+ion species (C) cholesterol as [M+H-HjO (m / z 369) ion at dynamic droplet / plasma conditions species under 8 s ramping times.

[0037] Figure 32 depicts (A) Total ion chromatogram of analysis of ubiquitin detected at dynamic droplet / plasma conditions (+2 kV DC) shown by Mass spectrum (B) representing [M+7H]+(m / z 1224) ion species as dominant charge state under 8 s ramping times.

[0038] Figure 33 depicts average APCI cycles with dominant cholesterol peak during 7- minute runs for lx, 1.5x, and 2x sputter-coated tips, lx showed the highest average (16.1 cycles), with 1.5x and 2x coatings lower (1.7 and 4.8 cycles).

[0039] Figure 34 depicts percentage of tips which provide 3 or more APCI cycles with dominant cholesterol peak during 7-minute runs for lx, 1.5x, and 2x sputter-coated tips.DETAILED DESCRIPTION

[0040] Before the present methods and systems are disclosed and described, it is to be understood that the methods and systems are not limited to specific synthetic methods, specific components, or to particular compositions. It is also to be understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting.

[0041] As used in the specification and the appended claims, the singular forms "a," "an" and "the" include plural referents unless the context clearly dictates otherwise. Ranges may be expressed herein as from "about" one particular value, and / or to "about" another particular value. When such a range is expressed, another embodiment includes- from the one particular value and / or to the other particular value. Similarly, when values are expressed as approximations, by use of the antecedent "about," it will be understood that the particular value forms another embodiment. It will be further understood that theendpoints of each of the ranges are significant both in relation to the other endpoint, and independently of the other endpoint.

[0042] "Optional" or "optionally" means that the subsequently described event or circumstance may or may not occur, and that the description includes instances where said event or circumstance occurs and instances where it does not.

[0043] Throughout the description and claims of this specification, the word "comprise" and variations of the word, such as "comprising" and "comprises," means "including but not limited to," and is not intended to exclude, for example, other additives, components, integers or steps. "Exemplary" means "an example of" and is not intended to convey an indication of a preferred or ideal embodiment. "Such as" is not used in a restrictive sense, but for explanatory purposes.

[0044] Disclosed are components that can be used to perform the disclosed methods and systems. These and other components are disclosed herein, and it is understood that when combinations, subsets, interactions, groups, etc. of these components are disclosed that while specific reference of each various individual and collective combinations and permutation of these may not be explicitly disclosed, each is specifically contemplated and described herein, for all methods and systems. This applies to all aspects of this application including, but not limited to, steps in disclosed methods. Thus, if there are a variety of additional steps that can be performed it is understood that each of these additional steps can be performed with any specific embodiment or combination of embodiments of the disclosed methods.

[0045] Disclosed herein are dynamic power supplies for the ionization and detection of compounds. The power supply can be used in three unique novel ion source, namely: (1) a single nano electrospray ionization (n ESI ), capable of both ESI and APCI for analysis of ultrasmall sample volumes, (2) a plasma-in-droplet ionization ( PI D I) source for flowthrough experiments where analyte solutions are pumped at relatively higher flowrate to enable implementation on liquid chromatography MS systems, and (3) flow-through induced paper spray ionization ( Fl PSI). By coupling the dynamic power supply independently to these ion sources, detection of both polar and nonpolar compounds, including both small molecules and biopolymers can be achieved in a single experiment, using a single emitter for all means of detection.

[0046] Disclosed herein are systems and methods of ionizing a compound in an analyte composition. In some implementations the system can be a dynamic nano-electrospray ionization. An exemplary dynamic nano electrospray (n ESI) setup is depicted in Figure 1. Insome implementations the system can include disposable sharp-end glass capillaries with outer conductive coating and dynamic power supply. Corona discharge is initiated by applying higher voltages (>4 kV) at pointed tips of capillaries (assisted by coating), generating plasma. This facilitates conventional n ESI at initial voltages (1-2 kV), which transits to plasma generation. At this point, the droplets from n ESI are exposed to corona discharge enabling APCI ionization. This method is applicable in both positive / negative-ion modes, enabling sequential detection of diverse analytes in complex mixtures / biofluids.

[0047] In some implementations, the dynamic power supply (Figure 29A) can apply electrical voltage (positive or negative) to ionization source with ramping capabilities, ranging from 0 to ±8 kV. This is a type of voltage waveform that increases and decreases in a linear fashion over time and automatically. The minimum percent value knob provides the minimum voltage to which it can ramp, for example, 0% will ramp from 0 to 8 kV, 25% will ramp from 2 to 8 kV and so on. The ramp period knob can be used to ramp for different time periods, for example 8, 75, 150, 225, and 300 s. These functions are activated when the ramp switch is turned on. When the ramp switch is turned off, this power supply operates a regular direct current (DC) voltage. The oscilloscope readings shown in Figure 29B demonstrate that ramping abilities are effective and can be controlled.

[0048] In some implementations the system (Figure 1) includes an emitter (101) having an inner diameter (102), a length (103); an inner surface, an outer surface, an inlet (104), and an outlet (105). In some implementations the outlet can include a tapered tip (106) which has an inner diameter smaller than the inner diameter of the emitter.

[0049] In certain implementations, the emitter is in electrical communication with a dynamic power supply (107). In certain implementations, the emitter is in electrical communication with a dynamic power supply (107) via a conductive wire (108). A continuous voltage sweep can be applied to the emitter in order to conduct conventional n ESI analysis and corona discharge mediated APCI ionization. In some implementations a first voltage that is less than 2 kV is applied to the emitter to generate charged droplets that exit the emitter through the outlet, followed by a second voltage that is greater than 4 kV to the emitter to generate a corona discharge. The second voltage is applied by performing a continuous voltage sweep from the first voltage to the second voltage. In certain implementations, the continuous voltage sweep is a linear sweep from the first voltage to the second voltage over a period of time.

[0050] In certain implementations, the linear sweep can be performed over a period of time from 0-300 s, from 0-240 s, from 0-180 s, from 0-120 s, from 0-60 s, from 0-30 s, from0-15 s, from 5-15 s, from 5-30 s, from 5-60 s, from 10-30 s, from 10-60 s, from 30-60 s, from 30-90 s, from 60-120 s, from 30-180 s, from 60-180 s, from 120-180 s, from 120-240 s, from 120-300 s, or from 180-300 s. When time = 0, the voltage change is instantaneous, rather than a sweep. In certain implementations, the linear sweep can be performed over a period of time from 0.1-300 s, from 0.1-240 s, from 0.1-180 s, from 0.1-120 s, from 0.1-60 s, from 0.1-30 s, or from 0.1-15 s.

[0051] In certain implementations, the conductive wire is configured to not contact the analyte composition. For example, the conductive wire is not disposed within the emitter.

[0052] In some implementations, the inner surface of the emitter includes an electrically non-conductive material and at least a portion of the outer surface of the emitter includes a conductive material (109), wherein the conductive material physically contacts the conductive wire. In certain implementations, the conductive coating is disposed towards the outlet of the emitter. In certain implementations at least the tapered tip is coated with a conductive material. In some implementations, the tapered tip and a portion of the emitter (having inner diameter (102)) is coated with the conductive material. In certain implementations, the conductive material cover from 5-95% of the surface area of the outer surface of the emitter, or from 5-75%, from 5-50%, from 5-40%, from 5-30%, from 5-20%, from 10-20%, from 10-30%, from 10-40%, from 10-50%, from 20-50%, from 20-40%, from 20-30%, from 30-75%, from 30-60%, from 30-50%, from 30-40%, from 40-75%, from 40-60%, from 40-50%, or from 50-75% of the surface area of the outer surface of the emitter.

[0053] In some implementations, the emitter is a glass capillary (i.e., thin tube). In some implementations, the conductive material is a conductive paint. In some implementations the conductive material is a metal foil wrapped around the emitter (e.g., around the glass capillary). In some implementations the conductive material is a metal, metal alloy or combination thereof.

[0054] In certain implementations, the conductive material can be Au, Pd, Pt, Cr, or a combination thereof. In certain preferred implementations, the conductive material is Au, Pd, a combination of Au and Pd, or an alloy or Au-Pd.

[0055] In some implementations the conductive material is coated on the emitter in a layer that has a thickness from 2-100 nm, from 10-100 nm, from 10-50 nm, from 10-25 nm, from 10-20 nm, from 15-25, from 25-50, or from 50-100 nm.

[0056] In some implementations the conductive material is deposited on the outer surface of the emitter using sputter coating. In an exemplary embodiment, the conductive material can be deposited on the emitter using sputter coating with a current of 30 mA and vacuumof IO-2mbar for a period about 60 seconds, for example 50-70 seconds. In some implementations the sputtering can be performed for a period of 15-75 second, 30-90 seconds, 45-65 second, 60-120 seconds, or 100-500 seconds. In other implementations the sputtering is performed for about 90 seconds, for example 80-100 seconds, or about 120 seconds, for example 110-130 seconds. The sputtering can be conducted at a sputter rate from 0.1-100 nm / min, 1-100 nm / min, from 1-50 nm / min, from 1-25 nm / min, from 1-10 nm / min, from 1-5 nm / min, from 5-10 nm / min, from 10-25 nm / min, from 25-50 nm / min, from 50-100 nm / min, or from 75-100 nm / min. The sputtering can be performed using one or more ingot(s) of the metal(s) and / or alloy(s) to be deposited on the emitter.

[0057] In certain implementations, the emitter can have a volume that is from 1 - 10 pl, 10- 250 pl, from 25-250 pl, from 50-250 pl, from 100-250 pl, from 10-100 pl, from 10-50 pl, from 25-75 pl, from 50-100 pl, or from 50-150 pl. The emitter can accommodate a volume of analyte composition. In some implementations the volume of the analyte composition is from 1-100 pl, from 1-50 pl, from 1-30 pl, from 1-10 pl, from 5-100 pl, from 5-50 pl, from 5- 25 pl, from 10-100 pl, from 10-50 pl, from 10-30 pl, from 10-25 pl, or from 25-50 pl.

[0058] The emitter (and outlet, tapered tip) of the emitter can be in fluid communication with an inlet (110) of a detector (111), preferably the detector is a mass spectrometer. The ionized compounds flow to the inlet for analysis. In certain implementations, the shortest distance between the outlet and the inlet of the detector is from 1-25 mm, from 1-10 mm, from 1-7.5 mm, from 1-5 mm, from 1-2.5 mm, from 2.5-25, from 2.5-10 mm, from 2.5-7.5 mm, from 2.5-5 mm, from 5-10 mm, or from 5-7.5 mm.

[0059] Also disclosed herein are systems and methods for dynamic plasma-in-droplet ionization (PI DI) mass spectrometry. An exemplary PIDI system is depicted in Figure 13. In certain implementations, the PIDI system can operate in ESI mode (pure charged microdroplets). In certain implementations, the PIDI system can operate in plasmamicrodroplet fusion mode. In certain implementations, the PIDI system can operate in both ESI and plasma-microdroplet fusion mode. The fusion of plasma with droplets can also be performed in two modes, Type I and II mode.

[0060] In certain implementations, the PIDI system does not include the use of gas (e.g., nebulizing gas (unlike ESI). In certain implementations, the PIDI system does not include external heating (unlike APCI). In certain implementations the electrical discharge co-exists with electrospray, offering versatile ionization mechanism for both small molecules and biopolymers (e.g., proteins) (Figure 14).

[0061] In certain implementations, the PIDI system includes a reservoir (201) in fluid communication with an emitter (202) having an outlet (203), wherein the emitter includes an electrically conductive tip (204) that includes the outlet. In certain implementations, the electrically conductive tip is connected to a dynamic power supply (205) through a conductive wire (206). In other implementations, a portion of the emitter other than the electrically conductive tip can be connected to the dynamic power supply.

[0062] In some implementations, the emitter (202) is a glass capillary (i.e., thin tube). In some implementations, the conductive material is a conductive paint. In some implementations the conductive material is a metal foil wrapped around the emitter (e.g., around the glass capillary). In some implementations the conductive material is a metal, metal alloy or combination thereof.

[0063] In certain implementations, the conductive material can be Au, Pd, Pt, Cr, or a combination thereof. In certain preferred implementations, the conductive material is Au, Pd, a combination of Au and Pd, or an alloy or Au-Pd.

[0064] In some implementations the conductive material is coated on the emitter in a layer that has a thickness from 2-100 nm, from 10-100 nm, from 10-50 nm, from 10-25 nm, from 10-20 nm, from 15-25, from 25-50, or from 50-100 nm.

[0065] The conductive material can be applied to the emitter using sputter coating as described above.

[0066] In some implementations, an analyte composition is delivered to the emitter from the reservoir, and a first voltage that is less than 2 kV is applied to the electrically conductive tip to generate charged droplets that exit the emitter through the outlet, and then a second voltage that is greater than 4 kV is applied to the electrically conductive tip to generate a corona discharge. In certain implementations the first voltage and second voltage are applied in a continuous voltage sweep from a voltage of less than 2 kV to a voltage of greater than 4 kV, wherein the continuous voltage sweep comprises a linear sweep from the first voltage to the second voltage over a period of time.

[0067] In certain implementations, the linear sweep can be performed over a period of time from 0-300 s, from 0-240 s, from 0-180 s, from 0-120 s, from 0-60 s, from 0-30 s, from 0-15 s, from 5-15 s, from 5-30 s, from 5-60 s, from 10-30 s, from 10-60 s, from 30-60 s, from 30-90 s, from 60-120 s, from 30-180 s, from 60-180 s, from 120-180 s, from 120-240 s, from 120-300 s, or from 180-300 s. When time = 0, the voltage change is instantaneous, rather than a sweep. In certain implementations, the linear sweep can be performed over a periodof time from 0.1-300 s, from 0.1-240 s, from 0.1-180 s, from 0.1-120 s, from 0.1-60 s, from 0.1-30 s, or from 0.1-15 s.

[0068] In certain implementations, the electrically conductive tip outlet is a sharp metal needle or etched silica capillary. Other conductive materials known in the art may also be used. In certain implementations, the electrically conductive tip is a metal needle having a gauge from 8-34, from 8-28, from 8-22, from 8-16, from 12-34, from 16-34, from 18-34, from 22-34, from 26-34, from 30-34, from 8-20, from 16-30, from 20-30, from 24-30, from 20-34, from 24-34, or from 28-34.

[0069] In some implementations of the PIDI system, the outlet is in fluid communication with an inlet (207) of a detector (208), preferably the detector is a mass spectrometer. In some implementations, the shortest distance between the outlet and the inlet of the detector is from 1-25 mm, from 1-10 mm, from 1-7.5 mm, from 1-5 mm, from 1-2.5 mm, from 2.5-25, from 2.5-10 mm, from 2.5-7.5 mm, from 2.5-5 mm, from 5-10 mm, or from 5- 7.5 mm.

[0070] In some implementations, the system may further include a purification device, for example a chromatography column such as used in HPLC-MS or LC-MS. In certain implementations, the analyte composition passes through a chromatography cylinder (209) before it reaches the emitter.

[0071] The system may further include gas supply (210), in fluid communication with the emitter. A gas may be provided to modulate the exit of charged microdroplets through the outlet. In some implementations, a reagent gas (e.g., HCI, CO, O2, O3, H2, etc) may combined with charged microdroplets.

[0072] Also disclosed herein are systems for flow-through induced paper spray ionization (FIPSI).

[0073] An exemplary FIPSI system is depicted in Figure 23. The system combines constant extraction / electrospray solvent flow to the paper tip with induced ionization mechanism. The continuous solvent flow to a cellulose substrate improves signal stability, repeatability, and acquisition time while the induced ionization mechanism allows high-throughput analysis. The induced ionization mechanism means that the voltage is not applied directly to the cellulose substrates (as typically done in traditions PSI). Instead, the voltage is applied to an electrically conductive tip. In certain implementations the sample (e.g., blood, urine, etc.) is placed on the cellulose paper substrate and dried prior to ionization. The extraction solvent is then supplied to the substrate containing the sample, which selectively extracts the analyte and transfers it to the proximal mass spectrometer. The extraction solvent canbe delivered continuously through dispenser. A supplied voltage can inductively ionize dissolved analyte by ESI or APCI mechanisms (or both). The prolonged analysis time and improved signal stability allow successful calibration curve to be obtained for cocaine (Figure 24) with excellent linearity (R2= 0.991) and low LOD (0.05 ng / mL). This sensitivity is better (one order of magnitude) than traditional PSI in biological fluids like urine, plasma, and blood (Figure 25). For instance, LOD for cocaine in urine was detected at 0.1 ng / mL level while PSI provided 1.5 ng / mL only for the same sample.

[0074] In certain implementations the FIPSI system can include: a) an analyte composition disposed on a cellulose substrate (301): b) a dispenser (302) comprising an outlet (303), wherein the outlet is positioned above (with respect to gravity) the cellulose substrate, wherein the dispenser does not contact the cellulose substrate; wherein the disperser is configured to deliver a solvent through the outlet to the cellulose substrate; c) an electrically conductive tip (304), wherein the electrically conductive tip does not contact the cellulose substrate, and wherein the electrically conductive tip is connected to a dynamic power supply (305) through a conductive wire (306). and d) applying a voltage to the electrically conductive tip.

[0075] In certain implementations a voltage can be applied to the electrically conductive tip as the solvent passes through the electrically conductive tip. The voltage can be a high voltage or a low voltage. In some implementations, the voltage is applied by performing a continuous voltage sweep from a first voltage to a second voltage, wherein the continuous voltage sweep comprises a linear sweep from the first voltage to the second voltage over a period of time.

[0076] In certain implementations, the linear sweep can be performed over a period of time from 0-300 s, from 0-240 s, from 0-180 s, from 0-120 s, from 0-60 s, from 0-30 s, from 0-15 s, from 5-15 s, from 5-30 s, from 5-60 s, from 10-30 s, from 10-60 s, from 30-60 s, from 30-90 s, from 60-120 s, from 30-180 s, from 60-180 s, from 120-180 s, from 120-240 s, from 120-300 s, or from 180-300 s. When time = 0, the voltage change is instantaneous, rather than a sweep. In certain implementations, the linear sweep can be performed over a period of time from 0.1-300 s, from 0.1-240 s, from 0.1-180 s, from 0.1-120 s, from 0.1-60 s, from 0.1-30 s, or from 0.1-15 s.

[0077] In certain implementations, the continuous voltage sweep is from first voltage of less than 2 kV to a second voltage of greater than 4 kV.

[0078] In certain implementations, the dispenser passes through the electrically conductive tip, such that the outlet is closer in distance to the cellulose substrate than the electrically conductive tip, such as in Figure 23. Such a system is described when the shortest distance between the outlet of the dispenser and the cellulose substrate is smaller than the shortest distance between the electrically conductive tip and the cellulose substrate. In certain implementations, the shortest distance between the electrically conductive tip and the outlet of the dispenser is from 0.1-10 mm, from 0.1-5 mm, from 0.1-2.5 mm, from 0.1-1.5 mm, from 0.1-1.0 mm, from 0.1-0.5 mm, from 0.5-5 mm, from 0.5-2.5 mm, from 0.5-1.5 mm, from 0.5-1 mm, from 1-5 mm, from 1-2.5 mm, from 1-1.5 mm, from 1.5-5 mm, from 1.5-2.5 mm, or from 2.5-5 mm. This distance may be regarded as the distance the dispenser extends beyond the electrically conductive tip.

[0079] In other implementations, the outlet is positioned within the electrically conductive tip. In this way, solvent is dispensed within the electrically conductive tip, and flows through the electrically conductive tip as it travels towards the cellulose substrate. Such a system is described when the shortest distance between the outlet of the dispenser and the cellulose substrate is greater than the shortest distance between the electrically conductive tip and the cellulose substrate.

[0080] In certain implementations, the electrically conductive tip outlet is a sharp metal needle or etched silica capillary. Other conductive materials known in the art may also be used. In certain implementations, the electrically conductive tip is a metal needle having a gauge from 8-34, from 8-28, from 8-22, from 8-16, from 12-34, from 16-34, from 18-34, from 22-34, from 26-34, from 30-34, from 8-20, from 16-30, from 20-30, from 24-30, from 20-34, from 24-34, or from 28-34.

[0081] In some implementations, the dispenser (302) is a glass capillary (i.e., thin tube). In some implementations, the conductive material is a conductive paint. In some implementations the conductive material is a metal foil wrapped around the dispenser (e.g., around the glass capillary). In some implementations the conductive material is a metal, metal alloy or combination thereof.

[0082] In certain implementations, the conductive material can be Au, Pd, Pt, Cr, or a combination thereof. In certain preferred implementations, the conductive material is Au, Pd, a combination of Au and Pd, or an alloy or Au-Pd.

[0083] In some implementations the conductive material is coated on the dispenser in a layer that has a thickness from 2-100 nm, from 10-100 nm, from 10-50 nm, from 10-25 nm, from 10-20 nm, from 15-25, from 25-50, or from 50-100 nm.

[0084] The conductive material can be applied to the dispenser using sputter coating as described above.

[0085] In certain implementations, the dispenser is made of a non-conductive material. In certain implementations, the dispenser is silica capillary or plastic tube, preferably the plastic is Teflon. In certain implementations, the dynamic power supply does not directly contact the disperser. In cases in which the dispenser contacts the electrically conductive tip, it may be said that the dispenser indirectly contacts dynamic power supply.

[0086] In some implementations, the solvent may be provided to the dispenser at a rate from 1-150 pl / min, from 1-100 pl / min, from 1-75 pl / min, from 1-50 pl / min, from 1-25 pl / min, from 1-10 pl / min, from 1-5 pl / min, from 5-100 pl / min, from 5-50 pl / min, from 5-25 pl / min, from 5-10 pl / min, from 10-100 pl / min, from 10-75 pl / min, from 10-50 pl / min, from 10-25 pl / min, from 25-100 pl / min, from 25-50 pl / min, from 50-150 pl / min, from 50-150 pl / min, or from 100-150 pl / min.

[0087] In certain implementations, the solvent may pass through the outlet at a rate from 1-150 pl / min, from 1-100 pl / min, from 1-75 pl / min, from 1-50 pl / min, from 1-25 pl / min, from 1-10 pl / min, from 1-5 pl / min, from 5-100 pl / min, from 5-50 pl / min, from 5-25 pl / min, from 5-10 pl / min, from 10-100 pl / min, from 10-75 pl / min, from 10-50 pl / min, from 10-25 pl / min, from 25-100 pl / min, from 25-50 pl / min, from 50-150 pl / min, from 50-150 pl / min, or from 100-150 pl / min.

[0088] In some implementations, the solvent is an aqeuous solvent (e.g., at least 50% water). In some implementations, the solvent is an organic solvent, e.g., a polar protic solvent, a polar aprotic solvent, or a non-polar solvent. Combinations of solvents may also be used. In certain implementations, the solvent is water, methanol, ethanol, isopropanol, methylene chloride, chloroform, diethyl ether, tetrahydrofuran, acetonitrile, acetone, ethyl acetate, methyl ethyl ketone, hexanes, toluene, or a combination thereof.

[0089] The cellulose substrate can be in fluid communication with an inlet (307) of a detector (308), preferably the detector is a mass spectrometer. The ionized compounds flow to the inlet for analysis. In certain implementations, the shortest distance between cellulose substrate and the inlet of the detector is from 1-25 mm, from 1-10 mm, from 1-7.5 mm, from 1-5 mm, from 1-2.5 mm, from 2.5-25, from 2.5-10 mm, from 2.5-7.5 mm, from 2.5-5 mm, from 5-10 mm, or from 5-7.5 mm.

[0090] In certain implementations, the cellulose substrate has a triangular shape, with one tip pointing towards a detector. In some implementations, the cellulose substrate is in the shape of an isosceles triangle, wherein the tip formed by the two sides of equal length ispointing towards a detector. In such implementations, the two sides of equal length will have a greater length than the other side. In some implementations, the length of one of the equal length sides is at least 1.2x, 1.5x, 1.75x, or 2x the length of the other side.

[0091] In certain implementations, the system includes a plurality of cellulose substrates, each including an analyte composition. The analyte may in each case be the same for each substrate, or in other implementations, different analyte compositions may be provided on different substrates. The substrates may be provided on a manifold configured to mechanically place the different cellulose substrates beneath (with respect to gravity) the outlet of the dispenser.

[0092] An exemplary dynamic FIPSI is depicted Figure 26, wherein a plurality of cellulose substrates are attached to a manifold, for example a robotic rotating disc. High-throughput dynamic flow-through induced paper spray ionization (HD-FIPSI) was successfully applied for the analysis of different classes of small and bio- molecules (Figure 27), namely ubiquitin (1), normorphine (2), [pTyr1146] insulin receptor (3), cocaine (4), and l-palmitoyl-2-oleoyl-sn- glycero-3-phosphocholine (5). The enhanced signal stability allowed to detect all of these compounds for 1.8 minutes only. Finally, cocaine and vitamin D2 mixture was successfully ionized and analyzed at ramping voltage conditions (Figure 28).EXAMPLES

[0093] The following examples are for the purpose of illustration of the invention only and are not intended to limit the scope of the present invention in any manner whatsoever.

[0094] Example 1: Dynamic nESI-MS

[0095] Preserving conventional n ESI functionalities, including soft ionization and minimal sample consumption, the dynamic spray mode introduces additional beneficial options. First, we optimized the dynamic spray setup with the compounds that only get ionized in ESI mode (polar), in only APCI mode (non-polar) and in both modes (intermediately polar) by ramping voltage. All the analytes were detected in mass spectrum with prevailing [M + H]+species and most of the non-polar molecules registered with M'+and [M + H - H2O]+ions. This facilitates automatic voltage tuning of non-polar molecules such as vitamin D2 (Figure 2) and cholesterol (Figure 3), whose ionization depends on voltage and glass tip variations (Figure 4). Detection of proteins like ubiquitin (Figure 5) and cytochrome c (Figure 6) in their native state was achieved during conventional ESI conditions. Starting with small molecule, the dynamic spray source has allowed the detection of vitamin D2 prepared with the concentration of 250 mM in methanol at higher voltages by ramping the voltage from 0 to 6 kV in positive ion mode. The mass spectrum of vitamin D2 (shown in Figure 2A) was acquiredwith M+* (m / z 397) and [M - HzO]+* (m / z 379) ion species. Their extracted ion chronograms show their occurrences at APCI mode only (4-6 kV).

[0096] The same ramping conditions (0 to 6 kV in positive ion mode) were applied for the 250 mM cholesterol sample in ethanol. The mass spectrum of cholesterol (shown in Figure 3A) was registered with [M + H - HzO]+(m / z 369) ion. The extracted ion chronogram of the cholesterol ion also demonstrates its occurrence in APCI mode alone but only for a specific voltage (around 5 kV) as compared to vitamin D2 (greater range from 4 to 6 kV).

[0097] The observation of distinct ionization thresholds for individual molecules has directed us to manually conduct voltage tuning using constant DC voltage supplied by MS instrument. It has been empirically demonstrated that ionization of cholesterol is highly voltage dependent, undergoing ionization within a narrow voltage range (4.55-5 kV) or highest signal intensity. Figure 4 illustrates mass spectra acquired through manual voltage incrementation, ranging from 1 to 6 kV, utilizing two distinct glass tips. I ntrigu ingly, observations indicate a substantial variation in ionization voltage dependent on the capillary characteristics, such as shape or size. Specifically, for the first tip, cholesterol detection occurs at >4.55 kV, while for the second tip, the signal appears at >5 kV. To address such variability, dynamic spray sources have been employed, adjusting the ionization voltage automatically regardless of analyte of interest or capillary emitter properties.

[0098] These different voltage ramping times have favorably impacted ionization efficiency. Especially in APCI mode, voltage ramping has been able to generate plasma in controlled manner where one ion species shows high signal intensity at particular voltage over other ions of same analyte. Additionally, the electrodeless mode has enabled excellent stability of glass tips and allowed long analysis time of minuscule sample volumes.

[0099] Our aim is to maintain traditional n ESI features, specifically soft ionization, without disturbing the native state of biomolecules. In order to achieve that, we analyzed proteins like ubiquitin (Figure 5) and cytochrome c (Figure 6) under dynamic spray conditions. Extracted ion chronogram shows that protein peaks are aquired in the n ES I regions. This affirms that dynamic spray works for polar molecules as well.

[0100] The important aspect behind this dynamic spray source was to determine the voltage corresponding to the time while acquiring the mass spectrum. It is required to determine the highest ionization efficiency for a defined voltage of analyte of interest as well as for examining the voltage-dependent variations in ionic species composition. We plotted the time to voltage conversion graphs plotted with SIM chronograms of methanolsolution containing 250 mM vitamin D2 at different ramping times, including 8 s (Figure 8), 75 s (Figure 9), 150 s (Figure 10), 225 s (Figure 11), and 300 s (Figure 12).

[0101] Collectively, our versatile source has shown its potential in the analysis of biofluid samples for metabolite profiling at low- and high-voltages to detect them in ESI and APCI ionization modes. Moreover, the simplicity and cost-effectiveness of our setup underscore its applicability in portable mass spectrometry, where selection of ionization sources and sampling interfaces is critical due to limited sample processing / introduction techniques. The novel aspect of this set-up is that ESI / APCI automatic voltage tuning and sequential detection of all-encompassing biomolecules is achieved under ambient conditions and from a single emitter.Example 2: Dynamic plasma-in-droplet ionization (PIDI) mass spectrometry

[0102] While the ESI-only mode allows us to perform all conventional ESI-MS detections, ESI / APCI mode opens up opportunity to analyze polar / nonpolar and small / big molecules (including proteins) simultaneously during complex mixtures analysis. For instance, we analyzed equimolar mixture of 5-fluorouracil, caffeine, 6-estradiol, cocaine, vitamin D2 and ubiquitin by ESI source at 5.5 kV (Figure 15). Here, just polar cocaine molecule with high proton affinity (930 kJ / mol) and big molecule ubiquitin were detected; all other analytes in the mixture including caffeine (with relatively high proton affinity, 914 kJ / mol) were completely suppressed. When analyzed with PIDI under the same spray voltage, the ionization of both polar and non-polar compounds from the spray plume occurred and all analytes were detected in the mass spectrum with prevailing (M + H)+species. Like typical APCI experiment, dehydration reactions involving (pseudo) molecular ions were also observed with 6-estradiol registering as [M+H-H2O]+species. Radical species M'+and (M - H2O),+were also detected for vitamin D2. Calibration curves with excellent linearity and low limit of detections (LOD) were constructed for polar cocaine (8 pg / mL LOD, Figure 16) and non-polar cholesterol (5.5 ng / mL LOD, Figure 17) analytes.

[0103] Moreover, we were able to detect proteins in the presence of nonthermal plasma (Figures 18 and 19) that can be explained by the uniquely soft nature of our plasma-droplet fusion system, compared with conventional APCI-MS. It is worth mentioning that ESI and APCI were previously distinct and incompatible processes. Our approach enabled these processes to co-exist efficiently, which improves analytical performance such as ionization efficiency, sensitivity, signal stability, and compatibility with HPLC. The hybrid ESI / APCI mode surprisingly showed higher sensitivity than conventional ESI-MS (Figure 20) that is not typical for any compromised dual ionization conditions. It was accomplished by optimized physicalparameters of the setup to instantaneously fuse and activate reactive plasma species to interact with charged microdroplet surface and gaseous ion species originating from the same source. Moreover, PIDI was tested for compatibility with high flowrates (Figure 21) and for applicability at dynamic voltage conditions (Figure 22). Thus, the new PIDI apparatus was successfully created to enable ESI and APCI mechanisms at high flowrates at constant and ramping voltage without using nebulizing gas and heating.Example 3: Dynamic flow-through induced paper spray ionization mass spectrometry

[0104] Paper Spray Ionization (PSI) is commonly employed for the analysis of small molecules in biological fluids, because of its simplicity, cost-effectiveness, speed, versatility, minimum sample size and sample preparation. Nevertheless, it has significant drawbacks as signal instability, low repeatability, and acquisition time as well as strong dependance of ionization efficiency on solvent and paper properties. To address some of these issues and make the PSI applicable for high-throughput analysis, we are proposing a new version of PSI, namely flow-through induced paper spray ionization ( Fl PSI). The FIPSI source itself is novel. It can be powered by traditional DC power supply or the new dynamic power supply. When powered by the dynamic power supply the system may be designated dynamic FIPSI.

[0105] The FIPSI setup (Figure 23) combines constant extraction / electrospray solvent flow to the paper tip with induced ionization mechanism. The continuous solvent flow to the paper substrate improves signal stability, repeatability, and acquisition time while the induced ionization mechanism allows high-throughput analysis. The induced ionization mechanism means that the voltage is not applied directly to the paper substrates (as typically done in traditions PSI). Instead, the voltage is applied to a sharp stainless steel needle, in which we have inserted the fused silica capillary used for solvent delivery. The sample (e.g., blood, urine, etc.) is placed on the cellulose paper substrate and dried prior to ionization. The extraction solvent is then supplied to the paper containing the sample, which selectively extracts the analyte and transfers it to the proximal mass spectrometer. The extraction solvent is delivered continuously by a syringe pump through a fused silica capillary placed inside of a sharp hollow needle. There is no direct physical contact of sharp needle with a sample present on the paper substrate. Sharp needle is connected to dynamic power supply; thus, the voltage can inductively ionize dissolved analyte by ESI or APCI mechanisms. The prolonged analysis time and improved signal stability allow successful calibration curve to be obtained for cocaine (Figure 24) with excellent linearity (R2= 0.991) and low LOD (0.05 ng / mL). This sensitivity is better (one order of magnitude) than traditional PSI in biological fluids like urine, plasma, and blood (Figure 25). For instance, LOD for cocainein urine was detected at 0.1 ng / mL level while PSI provided 1.5 ng / mL only for the same sample.

[0106] Dynamic FIPSI was modified further for high throughput analysis by its coupling it to robotic rotating disc (Figure 26). High-throughput dynamic flow-through induced paper spray ionization (HD-FIPSI) was successfully applied for the analysis of different classes of small and bio- molecules (Figure 27), namely ubiquitin (1), normorphine (2), [pTyr1146] insulin receptor (3), cocaine (4), and l-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (5). The enhanced signal stability allowed to detect all of these compounds for 1.8 minutes only. Finally, cocaine and vitamin D2 mixture was successfully ionized and analyzed at ramping voltage conditions (Figure 28). In conclusion, dynamic FIPSI platform was designed and constructed to obtain better performance than traditional PSI in terms of signal stability, repeatability, acquisition time, and sensitivity.Example 2: Fabrication of disposable, conductive borosilicate emitters

[0107] 60 Sixty pulled borosilicate glass capillaries were loaded into a custom-designed metal capillary holder and placed in the sputter coater chamber (Figure 30) Sputter coating was performed using a Q150T Plus Turbomolecular Pumped Coater, operating under a defined parameter profile, to deposit a uniform, conductive layer of gold-palladium onto the sharp tips. Optimization studies were conducted to identify the ideal coating thickness, resulting in three selected sputter durations: 5 minutes (lx), 7.5 minutes (1.5x), and 10 minutes (2x). For each coating thickness, 20 capillaries were prepared. Ten capillaries per group were used to analyze ethanolic solution containing cocaine (10 pM) and cholesterol (200 pM) in 10 pL samples. Each analysis was conducted over 7 minutes with dynamic voltage ramping from 0 to 6 kV over an 8-second period. The remaining ten capillaries per group were used for protein analysis with aqueous ubiquitin samples (100 pM, 10 pL), under identical voltage ramping and acquisition conditions. The sputter coating obtained under the lx conditions yielded a coating thickness of about 10-20 nm.

[0108] Sputter coating emerged as the promising method for tip preparation by enabling consistent plasma formation without evidence of adduct formation. This technique allowed the analysis of a broad range of molecular species, and its versatility was confirmed by the successful detection of mixture of polar cocaine and nonpolar cholesterol by ramping from 0 to 6kV through our dynamic power supply. Protein like ubiquitin has been successfully detected in n ESI regions indicating the conservation of n ESI properties. To quantitatively evaluate the performance of the conductive-coated capillary emitters, the average number of atmospheric pressure chemical ionization (APCI) cycles during which cholesterol was thedominant peak was measured. These experiments utilized a mixed solution of cocaine (10 pM) and cholesterol (200 pM) in ethanol, with ten capillaries analyzed per coating thickness (Figure 31). The number of APCI cycles was determined by examining the troughs in the total ion chromatogram (TIC), corresponding to APCI regions. Electrospray ionization (ESI) performance remained consistently high across all tips, regardless of coating thickness, indicating that observed differences in APCI performance were attributable to variations in plasma generation rather than ESI efficiency. Similarly, experiments using ubiquitin alone (100 pM in aqueous solution) demonstrated minimal variation in TIC performance across different coating thicknesses (Figure 32). Each tip was operated for 7 minutes while ramping the voltage from 0 to 6 kV in 8-second intervals.

[0109] The experimental findings demonstrated that capillaries with a lx sputter-coated gold-palladium (Au / Pd) layer exhibited superior plasma performance. Specifically, these emitters achieved an average of 16.1 APCI cycles per 7-minute run, wherein cholesterol was the dominant ion species (Figure 33). In contrast, capillaries with 1.5x and 2x, coating thicknesses yielded significantly fewer APCI cycles, averaging 1.7 and 4.8 cycles, respectively. This inverse relationship between coating thickness and plasma generation efficiency suggests that increased sputter deposition may alter the emitter tip's geometry or surface conductivity, thereby impeding effective plasma formation.

[0110] Further analysis depicted in Figure 34 revealed that 90% of the lx coated tips achieved at least three "good" APCI cycles-defined as cycles with cholesterol as the dominant peak-compared to only 20% in both the 1.5x and 2x coated tips. This benchmark of three cycles is considered sufficient for high-throughput applications. Additionally, it was observed that, in cases where the lx coated tips produced five or fewer APCI cycles, these occurred within the initial voltage ramps. This indicates that even brief operational periods are adequate for rapid analyses, underscoring the efficiency of the lx sputter-coated capillaries in dynamic spray mass spectrometry applications.ADDITIONAL EMBODIMENTS

[0111] A method for ionizing a compound in an analyte composition comprising: providing the analyte composition in an emitter (101) having an inner diameter (102), a length (103); an inner surface, an outer surface, an inlet (104), and an outlet (105), wherein the outlet comprises a tapered tip (106) having a smaller diameter than the inner diameter of the emitter; wherein the emitter is in electrical communication with a dynamic power supply (107) via a conductive wire (108);applying a first voltage that is less than 2 kV to the emitter to generate charged droplets that exit the emitter through the outlet; applying a second voltage that is greater than 4 kV to the emitter to generate a corona discharge; wherein the first voltage and second voltage are applied to the conductive wire and wherein the second voltage is applied by performing a continuous voltage sweep from the first voltage to the second voltage, wherein the continuous voltage sweep comprises a linear sweep from the first voltage to the second voltage over a period of time.

[0112] The method according to a preceding embodiment, wherein the period of time is from 0-300 s, from 0-240 s, from 0-180 s, from 0-120 s, from 0-60 s, from 0-30 s, from 0-15 s, from 5-15 s, from 5-30 s, from 5-60 s, from 10-30 s, from 10-60 s, from 30-60 s, from 30-90 s, from 60-120 s, from 30-180 s, from 60-180 s, from 120-180 s, from 120-240 s, from 120-300 s, or from 180-300 s.

[0113] The method according to a preceding embodiment, wherein the conductive wire is configured to not contact the analyte composition.

[0114] The method according to a preceding embodiment, wherein the conductive wire is not disposed within the emitter.

[0115] The method according to a preceding embodiment, wherein the inner surface comprises an electrically non-conductive material and at least a portion of the outer surface comprises a conductive material (109), wherein the conductive material physically contacts the conductive wire.

[0116] The method according to a preceding embodiment, wherein the portion of the outer surface comprising the conductive material extends from the tapered tip towards the inlet.

[0117] The method according to a preceding embodiment, wherein the tapered tip is coated with the conductive material.

[0118] The method according to a preceding embodiment, wherein the conductive material comprises from 5-95% of the surface area of the outer surface, or from 5-75%, from 5-50%, from 5-40%, from 5-30%, from 5-20%, from 10-20%, from 10-30%, from 10-40%, from 10- 50%, from 20-50%, from 20-40%, from 20-30%, from 30-75%, from 30-60%, from 30-50%, from 30-40%, from 40-75%, from 40-60%, from 40-50%, or from 50-75% of the surface area of the outer surface.

[0119] The method according to a preceding embodiment, wherein the inner surface of the emitter is glass.

[0120] The method according to a preceding embodiment, wherein the conductive material comprises a conductive paint.

[0121] The method according to any preceding embodiment, wherein the volume of the emitter is from 1 - 10, uL, 10-250 pl, from 25-250 pl, from 50-250 pl, from 100-250 pl, from 10-100 pl, from 10-50 pl, from 25-75 pl, from 50-100 pl, or from 50-150 pl.

[0122] The method according to any preceding embodiment, wherein the volume of the analyte composition is from 1-100 pl, from 1-50 pl, from 1-30 pl, from 1-10 pl, from 5-100 pl, from 5-50 pl, from 5-25 pl, from 10-100 pl, from 10-50 pl, from 10-30 pl, from 10-25 pl, or from 25-50 pl.

[0123] The method according to a preceding embodiment, wherein the outlet is in fluid communication with an inlet (110) of a detector (111), preferably the detector is a mass spectrometer.

[0124] The method according to a preceding embodiment, wherein the shortest distance between the outlet and the inlet of the detector is from 1-25 mm, from 1-10 mm, from 1-7.5 mm, from 1-5 mm, from 1-2.5 mm, from 2.5-25, from 2.5-10 mm, from 2.5-7.5 mm, from 2.5-5 mm, from 5-10 mm, or from 5-7.5 mm.

[0125] A method for ionizing a compound in an analyte composition comprising: providing the analyte composition disposed on a cellulose substrate (201): providing a solvent to the cellulose substrate from a dispenser (202) comprising an outlet (203), wherein the outlet is positioned above (with respect to gravity) the cellulose substrate, wherein the dispenser does not contact the cellulose substrate; wherein the solvent passes through an electrically conductive tip (204), wherein the electrically conductive tip does not contact the cellulose substrate, and wherein the electrically conductive tip is connected to a dynamic power supply (205) through a conductive wire (206); and applying a voltage to the electrically conductive tip.

[0126] The method according to a preceding embodiment, wherein the voltage is applied by performing a continuous voltage sweep from a first voltage to a second voltage, wherein the continuous voltage sweep comprises a linear sweep from the first voltage to the second voltage over a period of time.

[0127] The method according to a preceding embodiment, wherein the shortest distance between the outlet of the dispenser and the cellulose substrate is smaller than the shortest distance between the electrically conductive tip and the cellulose substrate.

[0128] The method according to a preceding embodiment, wherein the shortest distance between the outlet of the dispenser and the cellulose substrate is greater than the shortest distance between the electrically conductive tip and the cellulose substrate.

[0129] The method according to a preceding embodiment, wherein the period of time is from 0-8 s, 0-75 s, 0-150 s, 0-225 s, 0-300 s, 1-300 s, from 1-240 s, from 1-180 s, from 1-120 s, from 1-60 s, from 1-30 s, from 1-15 s, from 5-15 s, from 5-30 s, from 5-60 s, from 10-30 s, from 10-60 s, from 30-60 s, from 30-90 s, from 60-120 s, from 30-180 s, from 60-180 s, from 120-180 s, from 120-240 s, from 120-300 s, or from 180-300 s.

[0130] The method according to a preceding embodiment, wherein the dispenser is silica capillary or plastic tube, preferably the plastic is Teflon.

[0131] The method according to a preceding embodiment, wherein the dispenser passes through the electrically conductive tip and extends closer to the cellulose substrate, or wherein the solvent is delivered from the disperser into the electrically conductive tip.

[0132] The method according to a preceding embodiment, wherein the distance the dispenser extends beyond the sharp needle outlet is from 0.1-10 mm, from 0.1-5 mm, from 0.1-2.5 mm, from 0.1-1.5 mm, from 0.1-1.0 mm, from 0.1-0.5 mm, from 0.5-5 mm, from 0.5- 2.5 mm, from 0.5-1.5 mm, from 0.5-1 mm, from 1-5 mm, from 1-2.5 mm, from 1-1.5 mm, from 1.5-5 mm, from 1.5-2.5 mm, or from 2.5-5 mm.

[0133] The method according to a preceding embodiment, wherein the dynamic power supply does not contact the disperser.

[0134] The method according to a preceding embodiment, wherein the shortest distance between the cellulose substrate and the outlet of the dispenser or conductive tip, whichever is closer to the cellulose substrate, is from 0.1-10 mm, from 0.1-5 mm, from 0.1-2.5 mm, from 0.1-1.5 mm, from 0.1-1.0 mm, from 0.1-0.5 mm, from 0.5-5 mm, from 0.5-2.5 mm, from 0.5-1.5 mm, from 0.5-1 mm, from 1-5 mm, from 1-2.5 mm, from 1-1.5 mm, from 1.5-5 mm, from 1.5-2.5 mm, from 2.5-5 mm, from 2.5-7.5 mm, from 2.5-10 mm, from 5-7.5 mm, or from 5-10 mm.

[0135] The method according to any preceding embodiment, wherein applying the voltage comprises applying a continuous voltage sweep from the first voltage of less than 2 kV to the second voltage of greater than 4 kV.

[0136] The method according to a preceding embodiment, wherein the conductive tip outlet is a sharp metal needle, etched silica capillary, and other conductive sharp tips

[0137] The method according to a preceding embodiment, wherein the electrically conductive tip is a metal needle having a gauge from 8-34, from 8-28, from 8-22, from 8-16,from 12-34, from 16-34, from 18-34, from 22-34, from 26-34, from 30-34, from 8-20, from 16-30, from 20-30, from 24-30, from 20-34, from 24-34, or from 28-34.

[0138] The method according to a preceding embodiment, wherein the solvent is delivered to the dispenser at a rate from 1-150 pl / min, from 1-100 pl / min, from 1-75 pl / min, from 1- 50 pl / min, from 1-25 pl / min, from 1-10 pl / min, from 1-5 pl / min, from 5-100 pl / min, from 5- 50 pl / min, from 5-25 pl / min, from 5-10 pl / min, from 10-100 pl / min, from 10-75 pl / min, from 10-50 pl / min, from 10-25 pl / min, from 25-100 pl / min, from 25-50 pl / min, from 50-150 pl / min, from 50-150 pl / min, or from 100-150 pl / min.

[0139] The method according to a preceding embodiment, wherein the solvent exits the dispenser at a rate from 1-150 pl / min, from 1-100 pl / min, from 1-75 pl / min, from 1-50 pl / min, from 1-25 pl / min, from 1-10 pl / min, from 1-5 pl / min, from 5-100 pl / min, from 5-50 pl / min, from 5-25 pl / min, from 5-10 pl / min, from 10-100 pl / min, from 10-75 pl / min, from 10-50 pl / min, from 10-25 pl / min, from 25-100 pl / min, from 25-50 pl / min, from 50-150 pl / min, from 50-150 pl / min, or from 100-150 pl / min.

[0140] The method according to a preceding embodiment, wherein the cellulose substrate is affixed to a manifold comprising a plurality of cellulose substrates, wherein the manifold is configured to sequentially position each cellulose substrate in position to receive a solvent from the dispenser.

[0141] The method according to a preceding embodiment, wherein the solvent comprises water, methanol, ethanol, isopropanol, methylene chloride, chloroform, diethyl ether, tetrahydrofuran, acetonitrile, acetone, ethyl acetate, methyl ethyl ketone, hexanes, toluene, or a combination thereof.

[0142] The method according to a preceding embodiment, wherein the cellulose substrate is in fluid communication with an inlet of a detector, preferably in fluid communication with an inlet of a mass spectrometer.

[0143] The method according to a preceding embodiment, wherein the shortest distance between the cellulose substrate and the inlet of the detector is from 1-25 mm, from 1-10 mm, from 1-7.5 mm, from 1-5 mm, from 1-2.5 mm, from 2.5-25, from 2.5-10 mm, from 2.5- 7.5 mm, from 2.5-5 mm, from 5-10 mm, or from 5-7.5 mm.

[0144] A method for ionizing a compound in an analyte composition comprising: providing the analyte composition in a reservoir (201), wherein the reservoir is in fluid communication with an emitter (202), wherein the emitter comprises an outlet (203), wherein the emitter comprises an electrically conductive tip (204) defining the outlet;wherein the electrically conductive tip is connected to a dynamic power supply (205) through a conductive wire (206); delivering the analyte composition to the emitter; applying a first voltage that is less than 2 kV to the conductive tip to generate charged droplets that exit the emitter through the outlet; applying a second voltage that is greater than 4 kV to the conductive tip to generate a corona discharge; wherein the first voltage and second voltage are applied in a continuous voltage sweep from a voltage of less than 2 kV to a voltage of greater than 4 kV, wherein the continuous voltage sweep comprises a linear sweep from the first voltage to the second voltage over a period of time.

[0145] The method according to a preceding embodiment, wherein the period of time is from 0-8 s, 0-75 s, 0-150 s, 0-225 s, 0-300 s, 1-300 s, from 1-240 s, from 1-180 s, from 1-120 s, from 1-60 s, from 1-30 s, from 1-15 s, from 5-15 s, from 5-30 s, from 5-60 s, from 10-30 s, from 10-60 s, from 30-60 s, from 30-90 s, from 60-120 s, from 30-180 s, from 60-180 s, from 120-180 s, from 120-240 s, from 120-300 s, or from 180-300 s.

[0146] The method according to a preceding embodiment, wherein the electrically conductive tip is a metal needle, etched silica capillary, or other conductive sharp tips.

[0147] The method according to a preceding embodiment, wherein the electrically conductive tip is a metal needle having a gauge from 8-34, from 8-28, from 8-22, from 8-16, from 12-34, from 16-34, from 18-34, from 22-34, from 26-34, from 30-34, from 8-20, from 16-30, from 20-30, from 20-34, from 24-30, from 24-34, or from 28-34.

[0148] The method according to a preceding embodiment, wherein the outlet is in fluid communication with an inlet (207) of a detector (208), preferably the detector is a mass spectrometer.

[0149] The method according to a preceding embodiment, wherein the shortest distance between the outlet and the inlet of the detector is from 1-25 mm, from 1-10 mm, from 1-7.5 mm, from 1-5 mm, from 1-2.5 mm, from 2.5-25, from 2.5-10 mm, from 2.5-7.5 mm, from 2.5-5 mm, from 5-10 mm, or from 5-7.5 mm.

[0150] The method according to any preceding embodiment, wherein the analyte composition passes through a chromatography cylinder (209) before it reaches the emitter.

[0151] The method according to any preceding embodiment, wherein the emitter is in fluid communication with a gas supply (210).

[0152] The method according to any preceding embodiment, further comprising delivering a gas to the emitter through the conductive tip.

[0153] A system comprising: a chamber / assembly having an inlet and an outlet, wherein the inlet is silica capillary inserted in the outer conductive tip; the inner silica capillary does not physically contact the power suppler; and a power supply operably coupled to the outer conductive tip, wherein the power supply is configured to apply a continuous voltage sweep between a first voltage and a second voltage to the electrode, wherein the first voltage is less than 2kV and the second voltage is greater than 4kV.

[0154] The system according to any preceding embodiment, wherein the first voltage is less than zero volts.

[0155] The system according to any preceding embodiment, wherein the second voltage is less than zero volts.

[0156] The compositions and methods of the appended claims are not limited in scope by the specific compositions and methods described herein, which are intended as illustrations of a few aspects of the claims and any compositions and methods that are functionally equivalent are intended to fall within the scope of the claims. Various modifications of the compositions and methods in addition to those shown and described herein are intended to fall within the scope of the appended claims. Further, while only certain representative compositions and method steps disclosed herein are specifically described, other combinations of the compositions and method steps also are intended to fall within the scope of the appended claims, even if not specifically recited. Thus, a combination of steps, elements, components, or constituents may be explicitly mentioned herein or less, however, other combinations of steps, elements, components, and constituents are included, even though not explicitly stated. The term "comprising" and variations thereof as used herein is used synonymously with the term "including" and variations thereof and are open, nonlimiting terms. Although the terms "comprising" and "including" have been used herein to describe various embodiments, the terms "consisting essentially of" and "consisting of" can be used in place of "comprising" and "including" to provide for more specific embodiments of the invention and are also disclosed. Other than in the examples, or where otherwise noted, all numbers expressing quantities of ingredients, reaction conditions, and so forth used in the specification and claims are to be understood at the very least, and not as anattempt to limit the application of the doctrine of equivalents to the scope of the claims, to be construed in light of the number of significant digits and ordinary rounding approaches

Claims

CLAIMSWhat is claimed is:

1. A method for ionizing a compound in an analyte composition comprising: a) providing the analyte composition in an emitter (101) having an inner diameter (102), a length (103); an inner surface, an outer surface, an inlet (104), and an outlet (105), wherein the outlet comprises a tapered tip (106) having a smaller diameter than the inner diameter of the emitter; b) wherein the emitter is in electrical communication with a dynamic power supply (107) via a conductive wire (108); c) applying a first voltage that is less than 2 kV to the emitter to generate charged droplets that exit the emitter through the outlet; d) applying a second voltage that is greater than 4 kV to the emitter to generate a corona discharge; wherein the first voltage and second voltage are applied to the conductive wire and wherein the second voltage is applied by performing a continuous voltage sweep from the first voltage to the second voltage, wherein the continuous voltage sweep comprises a linear sweep from the first voltage to the second voltage over a period of time.

2. The method according to claim 1, wherein the period of time is from 0-300 s, from 0-240 s, from 0-180 s, from 0-120 s, from 0-60 s, from 0-30 s, from 0-15 s, from 5-15 s, from 5-30 s, from 5-60 s, from 10-30 s, from 10-60 s, from 30-60 s, from 30-90 s, from 60-120 s, from 30- 180 s, from 60-180 s, from 120-180 s, from 120-240 s, from 120-300 s, or from 180-300 s.

3. The method according to claim 1 or claim 2, wherein the conductive wire is configured to not contact the analyte composition.

4. The method according to any of claims 1-3, wherein the conductive wire is not disposed within the emitter.

5. The method according to any of claims 1-4, wherein the inner surface comprises an electrically non-conductive material and at least a portion of the outer surface comprises a conductive material (109), wherein the conductive material physically contacts the conductive wire.

6. The method according to claim 5, wherein the portion of the outer surface comprising the conductive material extends from the tapered tip towards the inlet.

7. The method according to claim 5 or 6, wherein the tapered tip is coated with the conductive material.

8. The method according to any of claims 5-7, wherein the conductive material comprises from 5-95% of the surface area of the outer surface, or from 5-75%, from 5-50%, from 5-40%, from 5-30%, from 5-20%, from 10-20%, from 10-30%, from 10-40%, from 10-50%, from 20- 50%, from 20-40%, from 20-30%, from 30-75%, from 30-60%, from 30-50%, from 30-40%, from 40-75%, from 40-60%, from 40-50%, or from 50-75% of the surface area of the outer surface.

9. The method according to any of claims 5-8, wherein the conductive material comprises a metal, metal alloy, or combination thereof.

10. The method according to any of claims 5-9, wherein the conductive material comprises Au, Pd, Pt, Cr, or a combination thereof.

11. The method according to any of claims 5-10, wherein the conductive material comprises an Au-Pd alloy.

12. The method according to any of claims 5-11, wherein the conductive material is coated on the emitter in a layer that has a thickness from 2-100 nm, from 10-100 nm, from 10-50 nm, from 10-25 nm, from 10-20 nm, from 15-25, from 25-50, or from 50-100 nm.

13. The method according to any of claims 5-12, wherein the conductive material is deposited on the outer surface of the emitter using sputter coating.

14. The method according to any of claims 1-13, wherein the inner surface of the emitter is glass.

15. The method according to claim 5 or 6, wherein the conductive material comprises a conductive paint.

16. The method according to any of claims 1-15, wherein the volume of the emitter is from 1 - 10, uL, 10-250 pl, from 25-250 pl, from 50-250 pl, from 100-250 pl, from 10-100 pl, from 10- 50 pl, from 25-75 pl, from 50-100 pl, or from 50-150 pl.

17. The method according to any of claims 1-16, wherein the volume of the analyte composition is from 1-100 pl, from 1-50 pl, from 1-30 pl, from 1-10 pl, from 5-100 pl, from 5-50 pl, from 5-25 pl, from 10-100 pl, from 10-50 pl, from 10-30 pl, from 10-25 pl, or from 25-50 pl.

18. The method according to any of claims 1-17, wherein the outlet is in fluid communication with an inlet (110) of a detector (111), preferably the detector is a mass spectrometer.

19. The method according to claim 18, wherein the shortest distance between the outlet and the inlet of the detector is from 1-25 mm, from 1-10 mm, from 1-7.5 mm, from 1-5 mm,from 1-2.5 mm, from 2.5-25, from 2.5-10 mm, from 2.5-7.5 mm, from 2.5-5 mm, from 5-10 mm, or from 5-7.5 mm.

20. A method for ionizing a compound in an analyte composition comprising: e) providing the analyte composition disposed on a cellulose substrate (201): f) providing a solvent to the cellulose substrate from a dispenser (202) comprising an outlet (203) and conductive tip, wherein the outlet is positioned above (with respect to gravity) the cellulose substrate, wherein the dispenser does not contact the cellulose substrate; g) wherein the solvent passes through an electrically conductive tip (204), wherein the electrically conductive tip does not contact the cellulose substrate, and wherein the electrically conductive tip is connected to a dynamic power supply (205) through a conductive wire (206); and h) applying a voltage to the electrically conductive tip.

21. The method according to claim 20, wherein the voltage is applied by performing a continuous voltage sweep from a first voltage to a second voltage, wherein the continuous voltage sweep comprises a linear sweep from the first voltage to the second voltage over a period of time.

22. The method according to claim 20 or 21 the shortest distance between the outlet of the dispenser and the cellulose substrate is smaller than the shortest distance between the electrically conductive tip and the cellulose substrate.

23. The method according to any of claims 20-22, wherein the shortest distance between the outlet of the dispenser and the cellulose substrate is greater than the shortest distance between the electrically conductive tip and the cellulose substrate.

24. The method according to any of claims 21-23, wherein the period of time is from 0-8 s, 0-75 s, 0-150 s, 0-225 s, 0-300 s, 1-300 s, from 1-240 s, from 1-180 s, from 1-120 s, from 1-60 s, from 1-30 s, from 1-15 s, from 5-15 s, from 5-30 s, from 5-60 s, from 10-30 s, from 10-60 s, from 30-60 s, from 30-90 s, from 60-120 s, from 30-180 s, from 60-180 s, from 120-180 s, from 120-240 s, from 120-300 s, or from 180-300 s.

25. The method according to any of claims 20-24, wherein the dispenser is silica capillary or plastic tube, preferably the plastic is Teflon.

26. The method according to any of claims 20-25, wherein the dispenser passes through the electrically conductive tip and extends closer to the cellulose substrate, or wherein the solvent is delivered from the disperser into the electrically conductive tip.U. The method according to any of claims 20-26, wherein the distance the dispenser extends beyond the conductive tip is from 0.1-10 mm, from 0.1-5 mm, from 0.1-2.5 mm, from 0.1- 1.5 mm, from 0.1-1.0 mm, from 0.1-0.5 mm, from 0.5-5 mm, from 0.5-2.5 mm, from 0.5-1.5 mm, from 0.5-1 mm, from 1-5 mm, from 1-2.5 mm, from 1-1.5 mm, from 1.5-5 mm, from 1.5-2.5 mm, or from 2.5-5 mm.

28. The method according to any of claims 20-27, wherein the dynamic power supply does not contact the disperser.

29. The method according to any of claims 20-28, wherein the shortest distance between the cellulose substrate and the outlet of the dispenser or conductive tip, whichever is closer to the cellulose substrate, is from 0.1-10 mm, from 0.1-5 mm, from 0.1-2.5 mm, from 0.1-1.5 mm, from 0.1-1.0 mm, from 0.1-0.5 mm, from 0.5-5 mm, from 0.5-2.5 mm, from 0.5-1.5 mm, from 0.5-1 mm, from 1-5 mm, from 1-2.5 mm, from 1-1.5 mm, from 1.5-5 mm, from 1.5-2.5 mm, from 2.5-5 mm, from 2.5-7.5 mm, from 2.5-10 mm, from 5-7.5 mm, or from 5- 10 mm.

30. The method according to any of claims 20-29, wherein applying the voltage comprises applying a continuous voltage sweep from the first voltage of less than 2 kV to the second voltage of greater than 4 kV.

31. The method according to any of claims 20-30, wherein the conductive tip outlet is a sharp metal needle, etched silica capillary, and other conductive sharp tips32. The method according to any of claims 20-31, wherein the electrically conductive tip is a metal needle having a gauge from 8-34, from 8-28, from 8-22, from 8-16, from 12-34, from 16-34, from 18-34, from 22-34, from 26-34, from 30-34, from 8-20, from 16-30, from 20-30, from 24-30, from 20-34, from 24-34, or from 28-34.

33. The method according to any of claims 20-32, wherein the solvent is delivered to the dispenser at a rate from 1-150 pl / min, from 1-100 pl / min, from 1-75 pl / min, from 1-50 pl / min, from 1-25 pl / min, from 1-10 pl / min, from 1-5 pl / min, from 5-100 pl / min, from 5-50 pl / min, from 5-25 pl / min, from 5-10 pl / min, from 10-100 pl / min, from 10-75 pl / min, from 10-50 pl / min, from 10-25 pl / min, from 25-100 pl / min, from 25-50 pl / min, from 50-150 pl / min, from 50-150 pl / min, or from 100-150 pl / min.

34. The method according to any of claims 20-33, wherein the solvent exits the dispenser at a rate from 1-150 pl / min, from 1-100 pl / min, from 1-75 pl / min, from 1-50 pl / min, from 1-25 pl / min, from 1-10 pl / min, from 1-5 pl / min, from 5-100 pl / min, from 5-50 pl / min, from 5-25 pl / min, from 5-10 pl / min, from 10-100 pl / min, from 10-75 pl / min, from 10-50 pl / min, from10-25 p.l / min, from 25-100 p.l / min, from 25-50 p.l / min7from 50-150 p.l / min7from 50-150 p.l / min, or from 100-150 p.l / m in.

35. The method according to any of claims 20-34, wherein the cellulose substrate is affixed to a manifold comprising a plurality of cellulose substrates, wherein the manifold is configured to sequentially position each cellulose substrate in position to receive a solvent from the dispenser.

36. The method according to any of claims 20-35, wherein the solvent comprises water, methanol, ethanol, isopropanol, methylene chloride, chloroform, diethyl ether, tetrahydrofuran, acetonitrile, acetone, ethyl acetate, methyl ethyl ketone, hexanes, toluene, or a combination thereof.

37. The method according to any of claims 20-36, wherein the conductive tip comprises a coating of conductive material.

38. The method according to claim 37, wherein the conductive material comprises from 5-95% of the surface area of the outer surface, or from 5-75%, from 5-50%, from 5-40%, from 5- 30%, from 5-20%, from 10-20%, from 10-30%, from 10-40%, from 10-50%, from 20-50%, from 20-40%, from 20-30%, from 30-75%, from 30-60%, from 30-50%, from 30-40%, from 40-75%, from 40-60%, from 40-50%, or from 50-75% of the surface area of the outer surface.

39. The method according to claim 37 or claim 38, wherein the conductive material comprises a metal, metal alloy, or combination thereof.

40. The method according to any of claims 37-39, wherein the conductive material comprises Au, Pd, Pt, Cr, or a combination thereof.

41. The method according to any of claims 37-40, wherein the conductive material comprises an Au-Pd alloy.

42. The method according to any of claims 37-41, wherein the conductive material is coated on the dispenser in a layer that has a thickness from 2-100 nm, from 10-100 nm, from 10-50 nm, from 10-25 nm, from 10-20 nm, from 15-25, from 25-50, or from 50-100 nm.

43. The method according to any of claims 37-42, wherein the conductive material is deposited on the outer surface of the dispenser using sputter coating.

44. The method according to any of claims 20-43, wherein the cellulose substrate is in fluid communication with an inlet of a detector, preferably in fluid communication with an inlet of a mass spectrometer.

45. The method according to claim 44, wherein the shortest distance between the cellulose substrate and the inlet of the detector is from 1-25 mm, from 1-10 mm, from 1-7.5 mm,from 1-5 mm, from 1-2.5 mm, from 2.5-25, from 2.5-10 mm, from 2.5-7.5 mm, from 2.5-5 mm, from 5-10 mm, or from 5-7.5 mm.

46. A method for ionizing a compound in an analyte composition comprising: i) providing the analyte composition in a reservoir (201), wherein the reservoir is in fluid communication with an emitter (202), wherein the emitter comprises an outlet (203), wherein the emitter comprises an electrically conductive tip (204) defining the outlet; wherein the electrically conductive tip is connected to a dynamic power supply (205) through a conductive wire (206); a) delivering the analyte composition to the emitter; b) applying a first voltage that is less than 2 kV to the conductive tip to generate charged droplets that exit the emitter through the outlet; c) applying a second voltage that is greater than 4 kV to the conductive tip to generate a corona discharge; wherein the first voltage and second voltage are applied in a continuous voltage sweep from a voltage of less than 2 kV to a voltage of greater than 4 kV, wherein the continuous voltage sweep comprises a linear sweep from the first voltage to the second voltage over a period of time.

47. The method according to claim 46, wherein the period of time is from 0-8 s, 0-75 s, 0-150 s, 0-225 s, 0-300 s, 1-300 s, from 1-240 s, from 1-180 s, from 1-120 s, from 1-60 s, from 1-30 s, from 1-15 s, from 5-15 s, from 5-30 s, from 5-60 s, from 10-30 s, from 10-60 s, from 30-60 s, from 30-90 s, from 60-120 s, from 30-180 s, from 60-180 s, from 120-180 s, from 120-240 s, from 120-300 s, or from 180-300 s.

48. The method according to claim 46 or 47, wherein the electrically conductive tip is a metal needle, etched silica capillary, coating of a conductive material, or other conductive sharp tips.

49. The method according to any of claims 46-48, wherein the electrically conductive tip is a metal needle having a gauge from 8-34, from 8-28, from 8-22, from 8-16, from 12-34, from 16-34, from 18-34, from 22-34, from 26-34, from 30-34, from 8-20, from 16-30, from 20-30, from 20-34, from 24-30, from 24-34, or from 28-34.

50. The method according to any of claims 46-48, wherein the electrically conductive tip comprises a coating of conductive material.

51. The method according to claim 50, wherein the conductive material comprises from 5-95% of the surface area of the outer surface, or from 5-75%, from 5-50%, from 5-40%, from 5-30% from 5-20% from 10-20% from 10-30% from 10-40% from 10-50% from 20-50% from 20-40%, from 20-30%, from 30-75%, from 30-60%, from 30-50%, from 30-40%, from 40-75%, from 40-60%, from 40-50%, or from 50-75% of the surface area of the outer surface.

52. The method according to claim 50 or claim 51, wherein the conductive material comprises a metal, metal alloy, or combination thereof.

53. The method according to any of claims 50-52, wherein the conductive material comprises Au, Pd, Pt, Cr, or a combination thereof.

54. The method according to any of claims 50-53, wherein the conductive material comprises an Au-Pd alloy.

55. The method according to any of claims 50-54, wherein the conductive material is coated on the emitter in a layer that has a thickness from 2-100 nm, from 10-100 nm, from 10-50 nm, from 10-25 nm, from 10-20 nm, from 15-25, from 25-50, or from 50-100 nm.

56. The method according to any of claims 50-55, wherein the conductive material is deposited on the outer surface of the emitter using sputter coating.

57. The method according to any of claims 46-56, wherein the outlet is in fluid communication with an inlet (207) of a detector (208), preferably the detector is a mass spectrometer.

58. The method according to claim 57, wherein the shortest distance between the outlet and the inlet of the detector is from 1-25 mm, from 1-10 mm, from 1-7.5 mm, from 1-5 mm, from 1-2.5 mm, from 2.5-25, from 2.5-10 mm, from 2.5-7.5 mm, from 2.5-5 mm, from 5-10 mm, or from 5-7.5 mm.

59. The method according to any of claims 46-58, wherein the analyte composition passes through a chromatography cylinder (209) before it reaches the emitter.

60. The method according to any of claims 46-59, wherein the emitter is in fluid communication with a gas supply (210).

61. The method according to any of claims 46-60, further comprising delivering a gas to the emitter through the conductive tip.

62. A system comprising: a chamber / assembly having an inlet and an outlet, wherein the inlet is silica capillary inserted in the outer conductive tip; the inner silica capillary does not physically contact the power suppler; and a power supply operably coupled to the outer conductive tip, wherein the power supply is configured to apply a continuous voltage sweep between a first voltage and a second voltage tothe electrode, wherein the first voltage is less than 2kV and the second voltage is greater than 4kV.

63. The system according to any preceding claim, wherein the first voltage is less than zero volts.

64. The system according to any preceding claim, wherein the second voltage is less than zero volts.

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