A method for evaluating the performance of a gas chromatograph mass spectrometer

Abstract

The present application belongs to the field of environmental analysis chemistry, and discloses a method for evaluating the performance of a gas chromatograph mass spectrometer. The evaluation method integrates multi-index instrument performance evaluation standard substances, and realizes accurate evaluation of the performance of the gas chromatograph mass spectrometer based on the standard curve of the target substance registered in the database. The evaluation method established by the present application can comprehensively evaluate the influence of instrument components such as the chromatographic column, the sample inlet and the mass spectrometer on the qualitative and quantitative analysis of target compounds through single injection, thereby saving the cost required for purchasing standard substances, manpower and time required for instrument testing, and having the advantages of high efficiency, convenient operation and low cost. The present application provides technical support for monitoring and controlling new pollutants, and has a wide application prospect.

Description

Technical Field

[0001] This invention belongs to the field of environmental analytical chemistry technology and relates to a method for evaluating the performance of a gas chromatography-mass spectrometry (GC-MS) instrument. Background Technology

[0002] With the widespread use of chemicals in industry, agriculture, and other fields, hundreds of thousands of synthetic chemical substances have been detected in the environment. To systematically assess the potential risks of these substances to ecosystems and human health, accurate quantitative analysis of their occurrence levels in various environmental media is necessary. To this end, various simultaneous analytical techniques have been developed and applied. Database-based high-throughput chemical analysis strategies integrate retention times, mass spectrometry information, and calibration curve data of target compounds during the database construction phase to establish a standardized database. Analytical methods generated based on this database can achieve simultaneous screening, identification, and accurate quantification of multiple organic pollutants in environmental samples in practical testing. In recent years, this strategy has been widely used in areas such as new pollutant identification and environmental pollution source tracing due to its high screening efficiency.

[0003] However, high-throughput analysis strategies based on databases still need improvement in quality control, especially in the analysis of samples from complex environments, where fluctuations in instrument status may affect the reliability and accuracy of database screening. For example, although a database of 887 organic pollutants developed based on the full-scan mode of gas chromatography-mass spectrometry has been successfully applied to multi-media sample screening [Kadokami K., Tanada K., Taneda K., et al.], it remains to be seen whether such databases can be improved. J Chromatogr A ,2005, 1089(1-2) [219-226], however, this method is susceptible to instrument drift in terms of retention time reproducibility and response intensity, which may lead to false positives or false negatives. Similarly, the full-scan method based on gas chromatography-quadrupole time-of-flight mass spectrometry has achieved high-throughput screening of 327 pesticides [Chang Q., Ge L., Li J., et al.]. Anal Methods 2021 13(46) [5660-5669], but its database construction relies on material fragment ion spectra generated by computational simulation. During the calibration process, the accuracy of qualitative identification may be affected by matrix interference or insufficient spectrum matching.

[0004] Database-based high-throughput analysis strategies are highly dependent on the stability of instrument performance. During long-term operation, instruments may experience problems such as inlet contamination, column aging, ion source contamination, and unstable collision cell (Q2) voltage. Taking ion source contamination as an example, this problem leads to reduced ionization efficiency of target analytes, affecting the sensitivity of the analytical method. All such issues impact the instrument's qualitative identification and quantitative analysis performance. Therefore, a systematic performance evaluation method for gas chromatography-mass spectrometry (GC-MS) is needed; this method is the technical foundation for ensuring stable instrument performance during long-term use. Summary of the Invention

[0005] This invention establishes a method for evaluating the performance of a gas chromatography-mass spectrometry (GC-MS) system, aiming to ensure the stability of various analytical methods based on this instrument during operation. These analytical methods include target analysis, non-target analysis, and suspected target analysis, hereinafter referred to as "analytical methods." This specification will specifically describe the substance retention time correction process and the performance evaluation process of each instrument component included in this evaluation method. The core objective of this invention is to systematically screen and compile a list of compounds prone to peak tailing, retention time shifts, or abnormal response intensities. Based on this list, a standard solution for instrument performance testing (CSTD) is prepared and tested. By analyzing the retention time deviation, accuracy, and other quantitative indicators of the compounds in the CSTD test data, a systematic performance evaluation of the GC-MS system is performed, thereby providing crucial verification evidence and technical assurance for the reliable operation of analytical methods.

[0006] The technical solution of the present invention: A method for evaluating the performance of a gas chromatography-mass spectrometry (GC-MS) system comprises the following steps: (1) Determine the chromatographic and mass spectrometric conditions for the gas chromatography-mass spectrometry system; Determine the chromatographic and mass spectrometric conditions for the gas chromatography-mass spectrometry (GC-MS): Ensure that the GC-MS conditions are consistent with those used when constructing the analytical method. (2) Determine the list of model compounds for evaluating the performance of the gas chromatography-mass spectrometry system; Methods for evaluating the performance of a gas chromatography-mass spectrometry (GC-MS) system include chromatographic performance evaluation, single-stage mass spectrometry performance evaluation, and tandem mass spectrometry performance evaluation. If the analytical method uses only full scan mode or selected ion monitoring mode, the GC-MS system only needs to undergo chromatographic performance evaluation and single-stage mass spectrometry performance evaluation. If the analytical method uses multiple reaction monitoring tandem mass spectrometry mode, the tandem mass spectrometry performance evaluation should be performed after completing the single-stage mass spectrometry performance evaluation. ①Chromatographic performance evaluation: Search for the retention time and retention index of substances generated during the construction of the analytical method, and screen for substances that may cause peak tailing or retention time shift due to differences in the state of the gas chromatography-mass spectrometry (GC-MS) instrument; the screened substances should cover different polarities, molecular weights and boiling point ranges; the screened substances should be used as standard substances for chromatographic performance evaluation. ② Single-stage mass spectrometry performance evaluation: Search the quantitative information of substances generated during the construction of the analysis method, and summarize the substances that are easily affected by the state of the ion source, resulting in a quantitative value deviation of more than 50%, as standard substances for single-stage mass spectrometry performance evaluation; Table 1 summarizes the list of compounds involved in assessments ① and ②, along with the assessment items and evaluation criteria for each substance. A CSTD (Computer-Oriented Study Target) was configured based on the compound list. The CSTD contains 54 compounds and 8 internal standards, namely: 4-chlorotoluene-D4, 1,4-dichlorobenzene-D4, naphthalene-D8, acenaphthene-D8, and acenaphthene-D8. 10 ,Philippines-D 10 fluoranthene-D 10 、䓛-D 12 Hobei-D 12 .

[0007] Table 1. Substances included in CSTD and their evaluation criteria

[0008] ③ Tandem Mass Spectrometry Performance Evaluation: The evaluation item is the collision voltage stability of the Q2 cell. Compounds sensitive to changes in collision voltage are selected as model compounds. In the mixed standard solution used, the concentration of each model compound is 1000 µg / L. The selection of model compounds is mainly based on: 1) Substances whose response intensity is sensitive to changes in collision voltage. These substances must meet the following requirements: maximum ion response intensity greater than 150,000, and response intensity variation exceeding 30,000 within ±3 eV of the optimal collision voltage. Based on this, the voltage range of 3 eV to 45 eV is divided into 7 voltage ranges in intervals of 6 eV. A representative model compound is selected for characterization in each voltage range, for a total of 7 substances. 2) Substances with unstable response signals, specifically divided into two types: the first type is where the response intensity of the pair with the largest response intensity is between 10,000 and 40,000, and the response intensity of the other two pairs is less than 10,000. Five model compounds are selected for evaluation in this case. The second type is where the maximum response intensity of all three pairs of ion pairs is less than 10,000. Five model compounds are selected for evaluation in this case. The substances involved in chromatographic performance evaluation, single-stage mass spectrometry performance evaluation, and tandem mass spectrometry performance evaluation are compiled into a performance test standard solution (CSTD) list, and the specific information is shown in Table 2.

[0009] Table 2. Materials and their evaluation criteria for Q2 collision voltage stability characterized by CSTD

[0010] (3) Prepare performance test standard solutions for sample testing to evaluate the performance of the gas chromatography-mass spectrometry system; Prepare mixed solutions of substances included in the CSTD list at concentrations of 100-1000 µg / L using n-hexane as the solvent; perform analysis using SIM mode; and evaluate the performance of the gas chromatography-mass spectrometry (GC-MS) system by assessing the analysis results; the evaluation includes correcting retention time and assessing the performance of the GC-MS system. Retention time correction uses C9-C 33 The predicted retention time of the target compound was calculated using n-alkanes by establishing a column flow rate and a perylene-D compound sensitive to changes in retention time. 12 Linear relationship of retention time deviation, and adjust column flow rate according to the linear relationship; The performance evaluation of a gas chromatography-mass spectrometry (GC-MS) system includes the condition of instrument components, mass spectrometer tuning stability, and Q2 cell collision voltage stability. Instrument components include the column, ion source, and liner. The condition of instrument components and mass spectrometer tuning stability are evaluated using compound accuracy. This is achieved by monitoring changes in the accuracy of compounds listed in the CSTD (Chemical Standards for Testing and Analysis) used to assess the condition of instrument components and the mass spectrometer tuning. When the accuracy of each compound is within the range of 70-130%, the performance of the instrument components and the mass spectrometer tuning meets the qualitative identification and quantitative analysis requirements of the analytical method. Q2 cell collision voltage stability is evaluated from two dimensions: the sensitivity of response intensity to changes in collision voltage and the stability of the response signal. When the accuracy of substances characterizing the sensitivity of response intensity to changes in collision voltage is within the range of 70-130%, and substances characterizing response signal stability are all detected, the instrument's Q2 cell collision voltage stability is considered to meet the qualitative identification and quantitative analysis requirements of the analytical method. (4) Maintain the components of the gas chromatography-mass spectrometry system based on the evaluation results; The maintenance content for instrument components is determined according to the condition of the instrument component. The maintenance content for each instrument component includes: 1) Ion source: cleaning, inspection or replacement of discharge needle and capillary tube; 2) Inlet: replacement of inlet liner and septum; 3) Chromatographic column: aging, cutting or replacement of chromatographic column.

[0011] Furthermore, the gas chromatography-mass spectrometry (GC-MS) system includes single quadrupole GC-MS, triple quadrupole GC-MS, ion trap GC-MS, time-of-flight mass spectrometry, and high-resolution GC-MS, all using gas as the mobile phase.

[0012] The performance evaluation of the gas chromatography-mass spectrometry system refers to assessing whether the gas chromatography-mass spectrometry system meets the requirements for qualitative identification and quantitative analysis of the analytical methods by evaluating retention time deviation and substance accuracy. The evaluation of instrument performance includes factors that affect the qualitative identification and quantitative analysis of the instrument, such as the accuracy of substance retention time, the condition of instrument components, tuning stability, and collision voltage stability; among which, instrument components include chromatographic columns, ion sources, and liners.

[0013] Furthermore, the qualitative identification is: based on the comparative analysis of the substance's retention time, retention index, and characteristic ion fragment information, to determine whether the substance exists in the sample; The quantitative analysis is as follows: Peak areas of compounds in the CSTD list are obtained by integrating the chromatograms of the compounds in the CSTD list; the content of the target analyte is calculated using the internal standard method; a linear equation Y = aX + b is obtained for each compound, where Y represents the ratio of the peak area of ​​the substance to the corresponding internal standard, and X represents the ratio of the concentration of the substance to the corresponding internal standard; the CSTD list is analyzed by gas chromatography-tandem mass spectrometry to obtain the peak area of ​​the sample to be tested; the concentration of compounds in the CSTD list is calculated based on the linear equation; and the accuracy of the compound is obtained by calculating the accuracy using the equation: accuracy = m / M, where m represents the calculated concentration of the compound, and M represents the concentration of the substance in the prepared CSTD list.

[0014] Furthermore, the analytical methods include target analysis methods, non-target analysis methods, and suspected target analysis methods applicable to gas chromatography-mass spectrometry.

[0015] Furthermore, the retention time correction adopts C9-C 33 The predicted retention time of the target compound was calculated using n-alkanes by establishing a column flow rate and a perylene-D compound sensitive to changes in retention time. 12 The linear relationship of retention time deviation was established, and the column flow rate was adjusted based on this linearity. By adjusting the column flow rate, perylene-D... 12 By controlling the retention time deviation to within 3 seconds (s), it can be ensured that the retention time deviation of all compounds in the mixed standard solution is less than 3 seconds. When perylene-D in CSTD... 12 When the retention time deviation is less than 3 seconds, it indicates that the instrument has completed the retention time calibration. Simultaneously with the retention time calibration, the instrument also performs a retention time accuracy assessment.

[0016] The retention time deviation is calculated using the equation: Retention Time Deviation = Predicted Retention Time - Measured Retention Time.

[0017] The beneficial effects of this invention are as follows: This invention constructs a method for evaluating the performance of gas chromatography-mass spectrometry (GC-MS). This method, by monitoring multiple indicators such as retention time deviation, instrument component status, and system tuning, enables rapid diagnosis and targeted maintenance of instrument performance, significantly improving maintenance efficiency and effectively reducing the incidence of false positives and false negatives in database-based high-throughput analysis. Furthermore, this evaluation method provides a reliable guarantee for the simultaneous identification and quantitative analysis of multiple new pollutants in environmental samples without relying on standards, laying a technical foundation for the long-term stable operation and reliable results of GC-MS-based analytical methods. Attached Figure Description

[0018] Figure 1 This is a flowchart for evaluating the performance status of an instrument using standard solutions for performance checks.

[0019] Figure 2 This is a diagram of the retention time deviation correction strategy.

[0020] Figure 3 This is a linear relationship graph of retention time and retention index for n-alkanes. Detailed Implementation

[0021] The specific embodiments of the present invention will be further described below with reference to the accompanying drawings and technical solutions.

[0022] Example 1 This embodiment uses a mixed standard solution containing 27 compounds as an example to demonstrate the implementation process of instrument retention time correction. The 27 compounds include major substance categories suitable for gas chromatography-mass spectrometry (GC-MS), such as alcohols, esters, and polycyclic aromatic hydrocarbons. This embodiment uses the mixed standard solution of 27 compounds to simulate actual analytical samples, and verifies the accuracy of CSTD in retention time correction by comparing the changes in the accuracy of each compound in the solution before and after CSTD evaluation.

[0023] The chromatographic and mass spectrometric conditions for the analytical methods are as follows: Chromatographic conditions: Column: SH-Rxi-5Sil MS (30 m × 0.25 mm × 0.25 µm); Injector temperature: 250℃; Injection mode: constant flow mode, splitless; Injection volume: 1 µL; Carrier gas: helium; Carrier gas flow rate: 1.2 mL / min; Transfer line temperature: 300℃; Mass spectrometry conditions: Ion source: EI source; Scan range: m / z 45 - 600; Solvent delay: 4 min; Temperature program: 40℃ (hold for 2 min), increase to 310℃ at 8℃ / min (hold for 5 min); The standards and reagents used in Example 1: n-Hexane; standard samples of substances contained in the CSTD mixed solution; mixed standard samples of 27 chemicals.

[0024] (1) Preparation of standard working solution A mixed solution containing 27 compounds from various categories, including alcohols, esters, and polycyclic aromatic hydrocarbons, was used as the test solution to verify whether the instrument met the requirements of the analytical method. Purchased standard samples were prepared into a CSTD mixture (500 µg / L) containing 54 substances and a mixed standard sample (500 µg / L) containing 27 chemicals, with n-hexane as the solvent. Determination was performed using gas chromatography-triple quadrupole mass spectrometry in SIM mode. (2) Correction retention time The retention times of 54 substances were measured using C9-C4 ... 33 The retention index of target compounds is calculated and corrected using n-alkanes, and the predicted retention time for each substance is obtained through the linear relationship between the retention index and retention time. For compounds whose retention time is significantly affected by column conditions, such as perylene-D... 12 If the retention time deviation is <3s, then the retention time deviation of each substance is considered to be <3s. For compounds whose retention time is significantly affected by column conditions, such as perylene-D... 12 If the retention time deviation is >3s, then the relationship between column flow rate and compound perylene-D can be established. 12 By maintaining the linear relationship of the time deviation, the required column flow rate value is calculated. After adjusting the column flow rate, the measurement is performed again to ensure perylene-D... 12 The retention time deviation is <3s; The retention times of the 54 CSTD substances before and after retention time correction are shown in Table 3: Table 3 Retention time deviation information for 54 CSTD substances

[0025] Comparing the retention time deviations of substances involved in the analytical method before and after calibration, the retention time deviations of all compounds after calibration were <3s. The instrument condition meets the qualitative identification performance requirements of the analytical method.

[0026] Table 4. Retention time deviation information of 27 compounds before and after correction.

[0027] Example 2 This embodiment addresses the state changes of the ion source in a gas chromatography-mass spectrometry (GC-MS) instrument, utilizing the ion source evaluation method of this invention. The GC-MS conditions and the mixed standard solution of 27 compounds are set as in Example 1. This embodiment uses the mixed standard solution of 27 compounds to simulate actual analytical samples. By comparing the changes in the accuracy of each compound in the solution before and after CSTD evaluation, the accuracy of CSTD in evaluating the ion source state is verified.

[0028] The standards and reagents used in Example 2: n-Hexane; a mixed standard sample of 27 compounds.

[0029] Specifically, the steps include the following: Before evaluating the instrument performance using CSTD, a mixed standard solution of 27 compounds at 500 µg / L was first tested. The results showed that 51.58% of the substances had an accuracy outside the 70-130% range, indicating that the instrument's condition did not meet the requirements for quantitative analysis. Subsequent CSTD testing showed that the accuracy of substances evaluating the ion source state was too low, and the evaluation failed. Based on this result, the ion source was cleaned and maintained, and the instrument was readjusted and CSTD tested again until the evaluation passed. The mixed standard solution of 27 compounds was then measured again, and the accuracy of all compounds was within the 70-130% range, achieving accurate quantification of the 27 compounds. The changes in the accuracy of substances evaluating the ion source state in CSTD are shown in Table 5, and the changes in the accuracy of the 27 compounds are shown in Table 6.

[0030] Table 5. Changes in the accuracy of the substances used to assess the state of the ion source in CSTD before and after assessment.

[0031] Table 6. Changes in accuracy of 27 compounds after ion source maintenance

[0032] This example demonstrates that CSTD can effectively assess the state of the ion source, and targeted maintenance can be performed on the instrument based on the assessment results to meet the performance requirements of the analytical method for quantitative analysis, thus improving the instrument's maintenance efficiency. The assessment process for other instrument components is the same as in this example.

[0033] Example 3 This embodiment demonstrates the use of CSTD to evaluate whether the collision voltage state of the Q2 cell meets the performance requirements of the analytical method for quantitative analysis. A mixed standard solution of 36 compounds was selected as the test solution for evaluating the voltage state of the Q2 collision cell. The retention times of the compounds in the solution cover different ranges from the optimal collision voltage. The instrumental chromatographic and mass spectrometric conditions were consistent with those in Example 1.

[0034] The standards and reagents used in Example 3: n-Hexane; a mixed standard sample of 36 compounds.

[0035] Specifically, the steps include the following: This embodiment verifies the CSTD's ability to assess the stability of the Q2 collision voltage through simulation experiments. Due to factors such as unstable collision gas pressure, electrode or cell contamination, and power supply / circuit failures, the Q2 collision voltage may experience systematic drift or random jumps. Systematic drift refers to continuous, directional changes in the collision voltage, the magnitude of which is independent of the collision voltage setting. Random jumps refer to discrete, undirected, and drastic changes in the collision voltage, without any discernible pattern. The "collision voltage-quantitative ion response intensity" curves of compounds suitable for gas chromatography-mass spectrometry analysis, such as alcohols, esters, and polycyclic aromatic hydrocarbons, exhibit an approximately Gaussian distribution, with a half-maximum width typically between 3 and 8 eV. This means that when the collision voltage change exceeds 3 eV, the quantitative ion response intensity may drop to half of the peak value, thus affecting the instrument's quantitative analysis performance. Therefore, this embodiment selects 3 eV as the collision voltage setting offset in the simulation experiment.

[0036] This embodiment simulates an abnormal state of systematic drift by lowering the Q2 cell collision voltage of the target analyte by 3 eV in the sampling method parameters, with the normal method without voltage reduction serving as a control. The accuracy of the CSTD and 36 compound standard solutions before and after the collision voltage modification is calculated. The changes in the accuracy of the substances in the CSTD evaluating the corresponding collision voltage range and the substances in the 36 compound standard solutions before and after the collision voltage reduction are compared to determine the evaluation effect of the substances in the CSTD evaluating the Q2 cell collision voltage performance. The changes are shown in Tables 7 and 8.

[0037] Table 7. Changes in the accuracy of the material characterizing the Q2 collision voltage before and after the Q2 collision voltage assessment.

[0038] Table 8. Changes in the accuracy of 36 compound standard solutions before and after Q2 collision voltage assessment.

[0039] First, when using the analytical method to determine 36 compound standard solutions (simulating actual samples), the accuracy of substance determination was generally low, and some substances were not detected, indicating that the instrument's condition no longer met the qualitative and quantitative performance requirements of the analytical method. Subsequently, a CSTD (Cyclic Structural Design Test) was used for evaluation, and the results showed that the accuracy of substance determination for the Q2 cell collision voltage performance was low, with some substances not detected, resulting in a failed evaluation. Based on this, targeted maintenance was performed on the instrument, and the CSTD test was repeated until the evaluation passed. Finally, the analytical method was used again to determine the 36 compound standard solutions, and the results showed that all previously undetectable substances were detected, with 92.68% of the substances having an accuracy within the range of 70–130%, confirming that the instrument's condition after maintenance met the requirements of the analytical method.

[0040] This invention is not limited to the above embodiments. Any technical modifications made according to the technical solutions of this invention fall within the scope of this invention as claimed.

Claims

1. A method for evaluating the performance of a gas chromatography-mass spectrometry (GC-MS) system, characterized in that, The steps are as follows: (1) Determine the chromatographic and mass spectrometric conditions for the gas chromatography-mass spectrometry system; Determine the chromatographic and mass spectrometric conditions for the gas chromatography-mass spectrometry (GC-MS): Ensure that the GC-MS conditions for the gas chromatography-mass spectrometry (GC-MS) are consistent with the GC-MS conditions used when constructing the analytical method; (2) Determine the list of model compounds for evaluating the performance of the gas chromatography-mass spectrometry system; Methods for evaluating the performance of gas chromatography-mass spectrometry (GC-MS) systems include chromatographic performance evaluation, single-stage mass spectrometry performance evaluation, and tandem mass spectrometry performance evaluation. If the analytical method uses only full scan mode or selected ion monitoring mode, then the gas chromatography-mass spectrometry system only needs to perform chromatographic performance evaluation and single-stage mass spectrometry performance evaluation; if the analytical method uses multiple reaction monitoring tandem mass spectrometry mode, then tandem mass spectrometry performance evaluation should be performed after completing the single-stage mass spectrometry performance evaluation. ①Chromatographic performance evaluation: Search for the retention time and retention index of substances generated during the construction of the analytical method, and screen for substances that may cause peak tailing or retention time shift due to differences in the state of the gas chromatography-mass spectrometry instrument; the screened substances need to cover different polarities, molecular weights and boiling point ranges; The screened substances were used as standard substances for chromatographic performance evaluation. ② Single-stage mass spectrometry performance evaluation: Search the quantitative information of substances generated during the construction of the analysis method, and summarize the substances that are easily affected by the state of the ion source, resulting in a quantitative value deviation of more than 50%, as standard substances for single-stage mass spectrometry performance evaluation; ③ Tandem Mass Spectrometry Performance Evaluation: The evaluation item is the collision voltage stability of the Q2 cell. Compounds sensitive to changes in collision voltage are selected as model compounds. In the mixed standard solution used, the concentration of each model compound is 1000 µg / L. The selection of model compounds is mainly based on: 1) Substances whose response intensity is sensitive to changes in collision voltage. These substances must meet the following requirements: maximum ion response intensity greater than 150,000, and response intensity variation exceeding 30,000 within ±3 eV of the optimal collision voltage. Based on this, the voltage range of 3 eV to 45 eV is divided into 7 voltage ranges in intervals of 6 eV. A representative model compound is selected for characterization in each voltage range, for a total of 7 substances. 2) Substances with unstable response signals, specifically divided into two types: the first type is where the response intensity of the pair with the largest response intensity is between 10,000 and 40,000, and the response intensity of the other two pairs is less than 10,000. Five model compounds are selected for evaluation in this case. The second type is where the maximum response intensity of all three pairs of ion pairs is less than 10,000. Five model compounds are selected for evaluation in this case. The substances involved in chromatographic performance evaluation, single-stage mass spectrometry performance evaluation, and tandem mass spectrometry performance evaluation are compiled into a performance test standard solution (CSTD) list. (3) Prepare performance test standard solutions for sample testing to evaluate the performance of the gas chromatography-mass spectrometry system; Prepare a mixed solution of 100-1000 µg / L of the substances included in the CSTD list, using n-hexane as the solvent; Samples are analyzed using SIM mode. The performance status of the gas chromatography-mass spectrometry (GC-MS) instrument is determined by evaluating the sample results. The evaluation includes calibrating retention time and assessing the performance of the GC-MS instrument. Retention time correction uses C9-C 33 The predicted retention time of the target compound was calculated using n-alkanes by establishing a column flow rate and a perylene-D compound sensitive to changes in retention time. 12 Linear relationship of retention time deviation, and adjust column flow rate according to the linear relationship; The performance evaluation of a gas chromatography-mass spectrometry (GC-MS) system includes the condition of instrument components, mass spectrometer tuning stability, and Q2 cell collision voltage stability. Instrument components include the column, ion source, and liner. The condition of instrument components and mass spectrometer tuning stability are evaluated using compound accuracy. This is achieved by monitoring changes in the accuracy of compounds listed in the CSTD (Chemical Standards for Testing and Analysis) used to assess the condition of instrument components and the mass spectrometer tuning. When the accuracy of each compound is within the range of 70-130%, the performance of the instrument components and the mass spectrometer tuning meets the qualitative identification and quantitative analysis requirements of the analytical method. Q2 cell collision voltage stability is evaluated from two dimensions: the sensitivity of response intensity to changes in collision voltage and the stability of the response signal. When the accuracy of substances characterizing the sensitivity of response intensity to changes in collision voltage is within the range of 70-130%, and substances characterizing response signal stability are all detected, the instrument's Q2 cell collision voltage stability is considered to meet the qualitative identification and quantitative analysis requirements of the analytical method. (4) Maintain the components of the gas chromatography-mass spectrometry system based on the evaluation results; The maintenance content for instrument components is determined according to the condition of the instrument component. The maintenance content for each instrument component includes: 1) Ion source: cleaning, inspection or replacement of discharge needle and capillary tube; 2) Inlet: replacement of inlet liner and septum; 3) Chromatographic column: aging, cutting or replacement of chromatographic column.

2. The method for evaluating the performance of a gas chromatography-mass spectrometry system according to claim 1, characterized in that, The gas chromatography-mass spectrometry (GC-MS) system includes single quadrupole GC-MS, triple quadrupole GC-MS, ion trap GC-MS, time-of-flight mass spectrometry, and high-resolution GC-MS, all using gas as the mobile phase.

3. The method for evaluating the performance of a gas chromatography-mass spectrometry system according to claim 1, characterized in that, The performance evaluation of the gas chromatography-mass spectrometry system refers to assessing whether the gas chromatography-mass spectrometry system meets the requirements for qualitative identification and quantitative analysis of the analytical methods by evaluating retention time deviation and substance accuracy. The evaluation of instrument performance includes factors that affect the qualitative identification and quantitative analysis of the instrument, such as the accuracy of substance retention time, the condition of instrument components, tuning stability, and collision voltage stability; among which, instrument components include chromatographic columns, ion sources, and liners.

4. The method for evaluating the performance of a gas chromatography-mass spectrometry system according to claim 3, characterized in that, The qualitative identification is: based on the comparative analysis of the substance's retention time, retention index, and characteristic ion fragment information, to determine whether the substance exists in the sample; The quantitative analysis is as follows: by integrating the chromatograms of compounds in the CSTD list, the peak areas of the compounds in the CSTD list are obtained, and the content of the target analyte is calculated by the internal standard method; the linear equation Y = aX + b is obtained for each compound, where Y represents the ratio of the response peak area of ​​the substance to the corresponding internal standard, and X represents the ratio of the concentration of the substance to the corresponding internal standard; the CSTD list is analyzed by gas chromatography-tandem mass spectrometry to obtain the response peak area of ​​the sample to be tested. The concentrations of compounds in the CSTD list are calculated using linear equations. The accuracy of the compounds is then calculated using the equation: Accuracy = m / M, where m represents the calculated concentration of the compound and M represents the concentration of the substance in the configured CSTD list.

5. The method for evaluating the performance of a gas chromatography-mass spectrometry system according to claim 1, characterized in that, The analytical methods include target analysis methods, non-target analysis methods, and suspected target analysis methods applicable to gas chromatography-mass spectrometry.

6. The method for evaluating the performance of a gas chromatography-mass spectrometry system according to claim 1, characterized in that, The retention time correction uses C9-C 33 The predicted retention time of the target compound was calculated using n-alkanes by establishing a column flow rate and a perylene-D compound sensitive to changes in retention time. 12 The linear relationship of retention time deviation was established, and the column flow rate was adjusted based on this linearity. By adjusting the column flow rate, perylene-D... 12 By controlling the retention time deviation to within 3 seconds (s), it can be ensured that the retention time deviation of all compounds in the mixed standard solution is less than 3 seconds. When perylene-D in CSTD... 12 When the retention time deviation is less than 3 seconds, it indicates that the instrument has completed the retention time calibration. Simultaneously with the retention time calibration, the instrument also performs a retention time accuracy assessment. The retention time deviation is calculated using the equation: Retention Time Deviation = Predicted Retention Time - Measured Retention Time.

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