648 results about "Mass spectrometric" patented technology

The invention discloses a micro proportional valve gradient composite coating and a preparation method thereof, and belongs to the technical field of micro proportional valve surface strengthening manufacturing. Aiming at the corrosion-resistant and wear-resistant requirements of the micro proportional valve under the working conditions of strong corrosion, multiple impurities and high pressure difference, the interface strengthening and corrosion-resistant and wear-resistant performance optimization of a metal matrix and a functional coating are combined, and metal / ceramic / polymer gradient material design, spraying parameter suitability research and a coating porosity / bonding strength control method are covered; the valve core and valve seat protection device is suitable for high-efficiency protection technical systems of valve cores and valve seats of precise instruments such as gas chromatographs and mass spectrometers.

The invention discloses a river nitrogen pollutant source analysis method based on drainage basin nitrogen turnover and isotope, and particularly relates to the technical field of water treatment.The river nitrogen pollutant source analysis method comprises the following steps that a drainage basin to be researched is selected, river water and soil samples in the drainage basin are systematically collected, and physical and chemical indexes and isotope indexes # imgabs0 # of the collected samples are tested. Nitrate marked by nitrogen isotope delta 15N / delta 18O and # imgabs1 # are used as key indication marks to perform high-precision identification on nitrogen sources in a river and an environmental system, the contribution proportion of different nitrogen sources to the nitrate concentration in a water body is quantified through a stable isotope analysis model, and the concentration of the nitrate in the water body is calculated. And in combination with data, the rates of denitrification and anaerobic ammonia oxidation in environmental samples, sediments and soil are directly measured through combined application of an isotopic tracer technology and a membrane inlet mass spectrometer technology.

A charge detection mass spectrometer includes an ion trap configured to store ions therein and to release stored ions therefrom, and an electrostatic linear ion trap (ELIT) array, in the form of at least two ELITs or ELIT regions each spaced apart from the ion trap, each ELIT or ELIT region including first and second ion mirrors and a charge detection cylinder positioned therebetween. The ion trap is controlled to release at least some of the stored ions to travel toward and into each of the ELITs or ELIT regions, and the first and second ion mirrors of each of the ELITs or ELIT regions is controlled in a manner which traps one or more ions traveling therein and causes the trapped ion(s) to oscillate back and forth between the first and second ion mirrors each time passing through and inducing a corresponding charge on the charge detection cylinder.

The invention discloses a method for rapidly and accurately determining the content of organochlorine pesticides in water, and belongs to the field of organochlorine pesticide content determination, and the method comprises the following steps: adding a regulator into a water sample, uniformly shaking, adding a substitute, and uniformly shaking again; adding sodium chloride into the water sample treated in the step S1, putting the water sample into a liquid-liquid extraction oscillator, and oscillating until the water sample is completely dissolved; s2, adding an extracting agent into the water sample treated in the step S2, vigorously oscillating, standing for layering, putting the lower-layer water sample into a reagent bottle, transferring an upper-layer extracting solution into a drying column, washing and dehydrating, and then transferring into a concentration bottle; the step S3 is executed again on the remaining water sample in the step S3; and S4, combining the eluents in the steps S3 and S4, transferring into a full-automatic nitrogen blowing instrument, concentrating to 1ml, adding an internal standard solution, and performing gas chromatography-mass spectrometer analysis after volume metering to obtain the content of the organochlorine pesticide in the water sample. The method has the beneficial effects that the method has the advantages of high efficiency, rapidness and accurate detection, and the method is simple to operate, low in cost and high in concentration efficiency and recovery stability.

The invention provides a 13C and 15N stable isotope labeled polypeptide abundance determination method based on a high-resolution mass spectrum, and belongs to the technical field of high-resolution mass spectrum determination. The determination method comprises the following steps: selecting a certified standard substance to calculate the system deviation delta 1 of the high-resolution mass spectrometer; calculating a theoretical relative deviation delta 2 of 13C and 15N isotopes in the 13C and 15N stable isotope labeled polypeptide according to a formula 2; collecting and recording a mass spectrum signal of a to-be-measured sample, and calculating to obtain an actual measurement relative deviation delta 3 of the to-be-measured sample; and when delta2 > delta3 > delta1, calculating the abundance value of the corresponding isotope label according to a formula 3 and a formula 4. According to the method disclosed by the invention, the flow injection sample is directly detected by adopting the high-resolution mass spectrometry, so that the detection speed is high, the high resolution is ensured, and the detection time is saved; only the response intensity and the m / z value of a target ion peak are needed for the analysis of a mass spectrum, and the operation is simple and convenient.

The invention discloses a method for detecting trace elements in a GH4169 high-temperature alloy by using secondary ion mass spectrometry, which specifically comprises the following steps: A1, firstly, carrying out necessary pretreatment on a GH4169 high-temperature alloy sample to remove surface pollution and an oxide layer; a2, selecting a time-of-flight secondary ion mass spectrometer, setting proper analysis parameters, and selecting a double-plasma O2 + ion source. The invention relates to the technical field of metal material trace chemical component analysis. According to the method for detecting the trace elements in the GH4169 high-temperature alloy by using the secondary ion mass spectrometry, a sample pretreatment process of the GH4169 high-temperature alloy is optimized, a double-plasma O2 + ion source and a low-energy electron gun charge compensation system of a time-of-flight secondary ion mass spectrometer are innovatively configured, deep analysis and a three-dimensional reconstruction algorithm are combined, and the trace elements in the GH4169 high-temperature alloy are detected. The sensitivity, the spatial resolution and the data reliability of trace element detection are obviously improved.

The invention provides an insulating oil gas mass spectrum analysis method and system. The method comprises the following steps: firstly, circulating vacuum degassing for one time, then deoiling and dehydrating the removed gas, introducing the deoiled and dehydrated gas into a mass spectrometry detection unit, carrying out primary detection, calling a self-adaptive algorithm and selecting proper circulating vacuum degassing times based on a primary detection result in combination with degassing temperature and degassing pressure of circulating vacuum degassing, and entering second-stage vacuum degassing; and deoiling and dehydrating the deoiled gas, and introducing the deoiled gas into a mass spectrometric detection unit for secondary detection to obtain a final detection result. According to the method, effective fusion of efficient degassing and rapid detection is realized, and reliable technical support is provided for rapid and accurate online monitoring and real-time fault diagnosis of the insulating oil dissolved gas.

The invention relates to the field of mass spectrometry, and describes a mass spectrometer based on multi-electrode coordination of a Jooden well. A multi-port ion source configured for multi-port input of electrons of ionization of gas molecules in a well and ions in an ion source outside the well, the ports being autonomously usable, comprising two external electrodes and four internal electrodes configured to excite periodic movement of ions in the well along an axis of symmetry and to detect signals caused by ions of secondary potential oscillation in the well, wherein ions are introduced into the trap from an external source with a slot, and ion movement is excited by applying an alternating voltage or the like to the electrodes. Or using a slot to introduce ions from an external source into a well in an external electrode, applying a potential to an internal electrode to create an electric field, the size of which is in a quadratic relationship with the coordinates, the electrodes having a specific equipotential surface geometry. Pulsed potentials can be applied to capture ions, multiple external ion sources can be equipped, and if the ion sources are not combined, each can be provided with a separate port. The mass spectrometer is uniquely designed in the aspects of ion input, excitation, detection, ion source configuration and the like.

The present invention relates to a method for quickly identifying white vaseline from different manufacturers based on silver salt-assisted laser desorption ionization-time of flight mass spectrometry, and belongs to the field of detection. Specifically comprising the following steps: S1, exploring and optimizing metal salt ion conditions, matrix conditions, and sampling methods, and using the optimized experimental conditions for sample preparation; S2, measuring the sample; S3, using eMSTAT Solution software for data analysis to achieve identification of white vaseline from different manufacturers. The method of the present invention replaces traditional organic matrices with silver salts, eliminates background interference, and improves the mass spectrometry signal-to-noise ratio; combines a direct smearing method to avoid complex solvent preparation and extraction, and is easy to operate; applies a mass spectrometer for mass spectrometry acquisition, has accurate molecular weight, reduces the detection time of each sample to 6 seconds, has high analytical throughput, and is low in cost, thereby achieving high-throughput, accurate, and rapid identification of large quantities of white vaseline from different sources.

The invention discloses a detection method for determining N-nitroso-Vonoprasan in Vonoprasan fumarate, and belongs to the technical field of medicine detection.The detection method comprises the steps that a solution is prepared, and detection is conducted; the detection comprises the following steps: determining a test solution and a reference solution by adopting a liquid chromatography-mass spectrometry method, recording a chromatogram, and calculating the content of N-nitroso-Vonorazan according to the chromatogram and an external standard method; according to the method, a triple quadrupole rod liquid phase mass spectrometer is adopted; a chromatographic column adopts octadecyl silane bonded silica gel as a filling agent, the specification of the chromatographic column is Poroshell 120EC-C18, 1.9 mu m, 50 mm * 3.0 mm; a mobile phase is composed of a mobile phase A and a mobile phase B, and gradient elution is adopted; the ultra-high pressure chromatographic column is adopted, the operation time is shorter, the signal-to-noise ratio is higher, the detection sensitivity is higher, the detection cost is lower, and the detection requirement can be met on a low-end triple quadrupole mass spectrum.

The invention relates to the field of glyceride structure analysis, in particular to a non-targeted analysis method and system for a glyceride structure based on a chromatography-mass spectrometry technology. The method comprises the following steps: constructing a molecular total composition database, a chain composition identification database and a carbon-carbon double bond position identification database; performing primary mass spectrometric detection on the glyceride sample to obtain a substance molecular weight, and comparing the substance molecular weight with the lipid molecular weight in the database to obtain total composition data; performing secondary mass spectrometric detection on the total composition data, comparing lipid chain hierarchy diagnosis ions with a database, and determining chain composition data and chain sn-position; performing photochemically derived secondary mass spectrometry on the chain composition data, and comparing lipid C = C diagnosis ions with a database to obtain C = C position information; in combination with total composition, chain composition, chain sn-position and C = C position information of glyceride, a biomedical research process is guided. According to the invention, non-targeted, rapid, comprehensive and high-throughput identification of total composition, chain composition, chain sn-position and C = C position of a complex glyceride sample is realized.

Systems and methods described herein provide for charge state control of multiply-charged anions in a front end, high pressure ion guide. In some example aspects, a mass spectrometer system is provided comprising a first vacuum chamber (121) maintained at a pressure above about 500 mTorr. At least one ion guide (106) is disposed within the first vacuum chamber, the at least one ion guide comprising a plurality of rods extending along a central longitudinal axis. A controller (193) is configured to adjust an amplitude of an RF voltage signal provided to the plurality of rods so as to alternatively operate the ion guide in a first mode of operation with a lower amplitude of the RF voltage signal so as to reduce the likelihood of charge reduction by electron detachment so as to substantially maintain the isotopic distribution of the ions during transmission of ions through the ion guide, and a second mode of operation with a higher amplitude of the RF voltage signal so as to increase the likelihood of electron detachment from ions being transmitted therethrough.

Disclosed is a method and device for the mass spectrometric quantification of two or more known target ion species, in which a mass spectrometric signal, composed of signal components of the two or more target ion species, which are not mass resolved in the mass spectrum, is weighted with quantification functions and summed, and a quantification parameter is determined for the two or more target ion species from the weighted sums.

The invention discloses a traditional Chinese medicine decoction piece full life cycle data management system and method, and relates to the field of data processing, and the method comprises the steps: collecting traditional Chinese medicine planting environment data through a sensor, and encrypting and storing the data through a block chain; in the processing link, the moisture evaporation condition is predicted through an LSTM neural network, and an early warning mechanism is set; in the processing process, the process is adjusted through a Raman spectrum; components and pesticide residues of the finished product are ensured to be qualified through mass spectrometric detection; the clinical end collects prescription and curative effect data optimization process; all data are synchronized through a block chain and a cross-chain protocol; through a data lake architecture and a graph neural network model, a planting area and a processing technology are optimized. The system has the advantages that through technologies such as a sensor, a block chain and an AI model, whole-process data tracing and optimization from planting to clinical use are realized, the quality and curative effect of a traditional Chinese medicine product are improved, and transparency and safety of the whole process are ensured.

The invention discloses a method for detecting 18 phthalic acid ester substances in brewed sauce, which specifically comprises the following steps: step 1, obtaining a sample of the brewed sauce to be detected, adding a phthalic acid ester substance internal standard working solution containing deuterated isotope and water, uniformly mixing, adding sodium chloride and acetonitrile, continuously uniformly mixing, and detecting the content of the phthalic acid ester substances in the brewed sauce to be detected; carrying out ultrasonic extraction treatment for 5-15 minutes, adding an ultrasonic extracting solution into a mixture of PSA, C18 and MgSO4, and carrying out centrifugal treatment to obtain supernate; 2, carrying out nitrogen blowing on the supernate until the supernate is nearly dry, and fixing the volume by using normal hexane to obtain a sample to be detected; and step 3, detecting by adopting a gas chromatography-tandem mass spectrometer isotope internal standard method.

Methods and systems are disclosed for predictive classification of a raw mass spectrum of a sample, the spectrum resulting from mass spectrometry analysis. The predictive classification is performed by a trained large-scale spectral model, including a self-supervised large-scale base spectral model trained with unidentified sample spectra from a plurality of sources and fine-tuned with a task-specific model trained with identified spectra.

The invention discloses a method for determining the content of trace holmium, thulium and tungsten in rare earth erbium and a compound thereof, which comprises the following steps: placing a rare earth erbium and compound sample thereof in a beaker, and performing a blank test along with a sample; adding nitric acid, heating at low temperature until the sample is completely dissolved, and cooling; transferring into a volumetric flask, adding a cesium internal standard solution, diluting with water, and uniformly mixing; the holmium, the thulium and the tungsten are measured by using an oxygen mode of an inductively coupled plasma tandem mass spectrometer, and the contents of the holmium, the thulium and the tungsten are calculated according to a working curve method. According to the method, the inductively coupled plasma tandem mass spectrometry technology is used, and mass spectrum interference of an erbium matrix on holmium, thulium and tungsten is effectively eliminated by selecting a proper reaction mode and optimizing the flow of reaction gas.

The present invention relates to a mass spectrometric method for determining isomeric amino acid residues of a peptide and comprises the steps of: generating a list of peptide candidates using the amino acid lead sequence of the peptide, said lead sequence comprising positions of determined amino acid residues and at least one position with undetermined isomeric amino acid residues; predicting the collision cross section for each peptide candidate; comparing the predicted collision cross section of each peptide candidate with an experimentally determined collision cross section of the peptide and assigning the isomeric amino acid residues of the best matching peptide candidate to the isomeric amino acid residues of the peptide.

One mode of a chromatograph mass spectrometer according to the present invention includes: a measurement unit (1) that includes a chromatograph unit (1A) and a mass spectrometry unit (1B) capable of performing MS / MS analysis, and collects chromatograph mass spectrometry data having three dimensions of time, m / z, and a signal intensity by repeatedly performing the MS / MS analysis by data independent analysis in the mass spectrometry unit on a sample containing a compound separated by the chromatograph unit; a component detection unit (42) that detects a compound and a component corresponding to a partial structure of the compound by obtaining MS / MS spectra of a bar graph presentation based on chromatograph mass spectrometry data over a predetermined m / z range for a target sample, estimating precursor ion peaks in each of the MS / MS spectra, and selecting peaks based on a predetermined standard regarding an m / z direction in each of the MS / MS spectra and a predetermined standard regarding a time direction for peaks that can be considered to be identical or an identical group on the MS / MS spectra; a narrowing unit (43, 44) that narrows down components to be analyzed by performing screening using prior information on the detected component; and a composition estimation unit (45) that, by using m / z information corresponding to a narrowed down component, estimate a composition or a chemical formula of the component.

The invention relates to the field of trace element detection, in particular to a system for detecting the concentration of trace elements in water. The gas chamber is connected with the atomization device, is internally provided with a light path capable of dynamically adjusting the White cell, and is used for enhancing a spectral absorption signal of the low-concentration trace elements; the light path modulation module is mounted on the side wall of the gas chamber; the temperature control module is used for adjusting the temperature of the optical element and the air chamber; the spectrum detection module is arranged behind the light outlet of the gas chamber and is used for detecting a spectrum signal after the aerosol is absorbed; the ionization and mass spectrum module comprises an ionization source and a mass spectrometer, the ionization source is used for ionizing the aerosol in the gas chamber into ions, and the mass spectrometer is used for separating the ions according to the mass-to-charge ratio and detecting the ions. According to the invention, a spectrum and mass spectrum combined technology is adopted, a water sample to be detected is atomized into aerosol water drops, and high-sensitivity detection of trace elements in water is realized by enhancing a spectrum absorption signal of low-concentration trace elements.

The invention relates to a hemoglobin peptide capable of promoting iron absorption and a preparation method thereof, the mass content of polypeptide in the hemoglobin peptide is greater than 90%, and the hemoglobin peptide contains at least one of FERF and FDGL; the preparation method comprises the following steps: S1, adding trisodium citrate into fresh animal blood, centrifuging, adding a NaCl solution for washing, preparing the solution, and performing high-pressure homogenization wall breaking for 2-5 times to obtain a hemoglobin solution; s2, adding 10-200 U / mL of neutral protease, carrying out heat preservation treatment, then adding 5-50 U / mL of flavourzyme, carrying out enzymolysis, and carrying out enzyme deactivation to obtain an enzymatic hydrolysate; s3, filtering with an ultrafiltration membrane, and collecting permeate; s4, adjusting the pH value, adding into an anion exchange chromatographic column, eluting with a NaCl solution, and collecting the eluent; s5, desalting, concentrating and drying to obtain hemoglobin peptide; and S6, carrying out mass spectrometric detection, and screening bioactive peptides to obtain the oligopeptide with the activity of promoting iron absorption. The hemoglobin peptide obtained by the preparation method disclosed by the invention has relatively good iron chelation capability and iron absorption promoting capability, and the bioavailability of iron ions can be remarkably improved.

And re-sampling triggered by uncertain results in mass spectrum screening. The invention provides a system / technical scheme for promoting repeated sample injection triggered by uncertain results in mass spectrum screening. In various embodiments, the system may access a screening list specifying a plurality of target compounds. In aspects, the system can classify a plurality of target compounds as present or absent in a sample, respectively, based on causing a chromatograph and a mass spectrometer to perform an iterative injection scheme on the sample, with subsequent iterations of the iterative injection scheme having progressive compound selectivity, and is triggered by the uncertain presence or absence of the classification result in the previous iteration.

The invention discloses a method for accurately measuring trace calcium in high-purity magnesium metal by combining membrane desolvation and triple quadrupole mass spectrometry, which comprises the following steps: (1) sequentially adding water to wet a high-purity magnesium sample and adding acid to dissolve the sample to obtain a digestion solution, and adding an internal standard solution into the digestion solution; (2) preparing calcium element solutions with multiple concentration gradients, adding the internal standard solution, fixing the volume, and shaking uniformly; (3) sequentially carrying out atomization treatment and membrane desolvation treatment on the prepared solution to respectively obtain dry aerosol of the to-be-detected solution and the standard solution; and (4) carrying out scanning determination on the dry aerosol of the solution to be detected and the standard solution in the step (3) by using a triple quadrupole mass spectrometer, and calculating to obtain the calcium content in the high-purity magnesium sample. According to the method, the 24Mg16O polyatomic interference brought by the matrix element and the mass spectrum interference of the working gas Ar on the to-be-detected element 40Ca are removed through membrane desolvation and triple quadrupole mass spectrometry, so that the trace calcium element in the high-purity magnesium sample can be accurately determined, and the lower determination limit can reach ppb level.

The invention discloses a method for detecting multiple perfluorinated compounds in a water environment. The method comprises the steps of sample collection and preservation, sample pretreatment and LC-MS / MS detection. According to the invention, trace detection is carried out on common perfluorinated compounds in a water environment by adopting solid-phase extraction-liquid chromatography-electrospray-tandem triple quadrupole mass spectrometer, a more perfect and comprehensive LC-MS / MS detection method for multi-medium concentration of perfluorinated compounds is provided, and on the premise that the recovery rate and the accuracy of a detection result are ensured, the detection efficiency is improved. The sample pretreatment modes in different media are optimized and adjusted, so that the experiment process is more convenient and faster, time and labor are saved, the use of traditional glass material consumables is avoided, and the experiment error is reduced; meanwhile, the method disclosed by the invention is wider in application range, can meet trace detection of perfluorinated compounds in surface water, underground water, domestic sewage, industrial wastewater, river sediment and residual sludge of a sewage plant, and provides data support for quality supervision and risk early warning in a water environment.

Methods are described for determining the amount of insulin in a sample. More specifically, mass spectrometric methods are described for detecting and quantifying insulin in a biological sample utilizing purification methods coupled with tandem mass spectrometric or high resolution / high accuracy mass spectrometric techniques.

The invention belongs to the technical field of antibiotic detection, and particularly discloses a synchronous detection method for 42 antibiotics in estuary multi-environment media. The method comprises the following steps: mixing an estuary sample to be detected, a phosphate buffer solution and a methanol-acetonitrile solution of formic acid, carrying out multiple times of ultrasonic extraction, combining extract liquids obtained by the multiple times of ultrasonic extraction, sequentially carrying out pH value regulation and concentration, and then adding water for dilution, so as to obtain an extraction diluent; then carrying out purification treatment on the extraction diluent by adopting a solid-phase extraction method to obtain a to-be-detected solution; adding five antibiotic internal standards into the to-be-detected solution, fixing the volume, detecting the to-be-detected solution by adopting an ultra-high performance liquid chromatography tandem mass spectrometer, and performing data processing on a detection result to obtain the concentration of 42 antibiotics in the to-be-detected estuary sample. The test method disclosed by the invention can be used for trace detection of antibiotics in a complex environmental medium in an estuary region, has the characteristics of low detection limit, good reproducibility and relatively high recovery rate, and can meet analysis requirements.

A system includes a first pre-separation device configured to perform a first pre-separation of precursor ions according to mobilities of the precursor ions and a second pre-separation device positioned downstream of the first pre-separation device configured to perform a second pre-separation of precursor ions based on a mass-to-charge ratio (m / z) of the precursor ions. The system further includes a mass spectrometer positioned downstream of the second pre-separation device configured to acquire mass spectra for precursor ions emitted from the second pre-separation device. The second pre-separation device is synchronized with the mass spectrometer such that an m / z range of precursor ions emitted from the second pre-separation device corresponds to a precursor m / z isolation window of the mass spectrometer.

The method, the composition and the kit provided by the invention provide a signal amplification method for detecting target biomolecules, and the sensitivity of detecting by using target binding ligand molecules is remarkably improved. These methods include adding nucleic acid repeat cycles to, for example, a target binding molecule, thereby providing a plurality of landing pads for the labeled probe. These methods are well suited for multiplex detection, so that multiple targets can be sensitively detected in one detection. The methods and compositions can be applied to the fields of imaging, flow cytometry, mass spectrometers / CyTOF and the like, and provide additional tools for research and diagnosis purposes.

The invention discloses a method for fixed-point detection of the content of doped elements in crystalline silicon, and relates to the technical field of mass spectrometric detection. Secondary ion mass spectrometry and inductively coupled plasma mass spectrometry are combined to carry out fixed-point detection on the content of the doped elements in a certain ion depth in crystalline silicon containing the doped elements. Specifically, secondary ion mass spectrometry is adopted to detect the unit signal intensity of a crystalline silicon sample and calculate the total signal intensity, inductively coupled plasma mass spectrometry is adopted to detect the total content of doped elements in the crystalline silicon sample, and the unit signal intensity u [beta], the total signal intensity and the total content of the doped elements are utilized to determine the content of the doped elements in the crystalline silicon sample. And calculating to obtain the doped element content in the crystalline silicon sample under a certain ion depth. According to the method, the secondary ion mass spectrometry and the inductively coupled plasma mass spectrometry are combined to realize quantitative fixed-point analysis of the doped elements, so that the detection accuracy is ensured, the use of a standard sample in the secondary ion mass spectrometry is avoided, and the use limitation of the standard sample in detection of the element distribution content is overcome.

The invention belongs to the technical field of medicine detection, and particularly relates to a method for detecting a nitroso compound in a raw material medicine in a riptacaine emulsifiable paste, which comprises the following steps: preparing a test sample: taking the riptacaine emulsifiable paste, adding a 5mol / L sodium hydroxide solution, uniformly mixing, then adding a 5mol / L hydrochloric acid solution, and uniformly mixing; diluting with a solvent with the pH value of 7.20 + / -0.02, and then centrifugally filtering to obtain a test sample; wherein the solvent is a mixed solvent composed of monopotassium phosphate and acetonitrile; liquid chromatography separation: the tested sample is separated by liquid chromatography, and a mobile phase A is a 0.2% formic acid solution; the mobile phase B is methanol; the chromatographic column is SB-C18, 2.1 * 100 mm, 1.7 [mu] m; and mass spectrum detection: detecting the substance separated by the liquid chromatography by using a mass spectrometer to obtain the content of the nitroso compound. The detection method is efficient, sensitive and excellent in reproducibility.