Pesticide residue quantitative determination method and system

Abstract

The invention relates to the field of pesticide residue detection, in particular to a pesticide residue quantitative determination method and system.The method comprises the steps that the retention time of an internal standard substance is obtained, the retention time of to-be-detected pesticide is corrected according to the retention time of the internal standard substance, and the time range of eluent collection is determined according to the retention time of the internal standard substance and the retention time of the to-be-detected pesticide; after uniformly mixing the eluents, obtaining mass spectrograms of the internal standard substance and the pesticide to be detected through a mass spectrometer; determining a ratio of a preset peak area to an actual peak area in a chromatogram output by the detector according to the concentration of the internal standard substance, performing modal decomposition on the chromatogram output by the detector, gradually approaching the ratio to a target value according to a decomposition result, and obtaining an adjusted chromatogram; and correcting the mass spectrum of the pesticide to be detected by using the mass spectrum information of the internal standard substance, and calculating the content of the pesticide to be detected by using the adjusted chromatogram and the corrected mass spectrum.

Description

Technical Field

[0001] The present invention relates to the field of pesticide residue detection, and in particular to a method and system for quantitatively determining pesticide residues. Background Art

[0002] The widespread use of pesticides inevitably leads to the problem of pesticide residues in agricultural products and the environment, which directly threatens human health and ecological environment safety. Pesticide residues may enter the human body through the food chain, causing acute or chronic poisoning reactions, and may lead to the occurrence of certain chronic diseases, cancer and reproductive health problems. Therefore, effective monitoring of pesticide residues in agricultural products has become an important issue in the field of global food safety. Countries have established pesticide residue limit standards and increased the intensity of pesticide residue monitoring to ensure food safety.

[0003] High performance liquid chromatography has become one of the main technologies for accurate detection of pesticide residues due to its advantages such as high sensitivity, good separation effect and strong selectivity. The operation process of HPLC is relatively simple and can quickly separate and quantitatively analyze complex compounds, making it particularly suitable for the simultaneous detection of multiple pesticides. In recent years, the detection technology of HPLC has been continuously innovated. By combining with detectors such as mass spectrometry (MS), the accuracy and sensitivity of detection have been significantly improved, and it can effectively identify extremely trace amounts of pesticide residues. In addition, HPLC has a high degree of automation and can realize batch processing of samples, which provides great convenience for large-scale monitoring of pesticide residues. However, due to environmental noise, measurement errors, etc., errors are inevitable in the determination of pesticide residue content. How to reduce the impact of noise and improve the accuracy of measurement is an urgent problem to be solved. Summary of the invention

[0004] In view of the deficiencies in the prior art, the present invention provides a method and system for quantitative determination of pesticide residues to improve the accuracy of pesticide residue detection.

[0005] In a first aspect, the present invention provides a method for quantitative determination of pesticide residues, the method comprising: Obtaining the retention time of the internal standard, using the retention time of the internal standard to calibrate the retention time of the pesticide to be tested, determining the time range for collecting the eluent according to the retention times of the internal standard and the pesticide to be tested, and obtaining the mass spectra of the internal standard and the pesticide to be tested by a mass spectrometer after the eluents are evenly mixed; Determine the ratio of the preset peak area to the actual peak area in the chromatogram output by the detector according to the concentration of the internal standard, perform modal decomposition on the chromatogram output by the detector, gradually approach the ratio to the target value according to the decomposition result, and obtain an adjusted chromatogram; The mass spectrum of the pesticide to be tested is corrected using the mass spectrum information of the internal standard, and the content of the pesticide to be tested is calculated using the adjusted chromatogram and the corrected mass spectrum.

[0006] Preferably, the retention time of the pesticide to be tested is corrected using the retention time of the internal standard, specifically: Calculate the difference between the estimated retention time and the actual retention time of the internal standard; The sum of the estimated retention time of the pesticide to be tested and the difference is taken as the corrected retention time of the pesticide to be tested.

[0007] Preferably, the time range for collecting the eluate is determined according to the retention time of the internal standard and the pesticide to be tested, specifically: When the peak starting point of the internal standard or the pesticide to be tested is detected, the time interval between the peak starting point and the retention time is determined, and the time when the peak starting point passes half of the time interval is used as the starting point of the time range for collecting the eluate; The time difference between the starting point and the maximum peak height is calculated, and the maximum peak height time plus the time difference is used as the end point of the time range for collecting the eluate.

[0008] Preferably, the ratio is gradually approached to a target value according to the decomposition result, and an adjusted chromatogram is obtained, specifically: Calculate the approximate entropy of the chromatogram output by the detector, and determine the number of eigenmode functions selected from the front to the back according to the approximate entropy; Setting an adjustment coefficient for each selected intrinsic mode function, and calculating the sum of the products of all selected intrinsic mode functions and the corresponding adjustment coefficients; The chromatogram output by the detector is subtracted from the sum to obtain a new chromatogram, and the ratio of the preset peak area to the peak area of ​​the internal standard in the new chromatogram is calculated, and the adjustment coefficient is continuously adjusted to gradually approach the target value. When the preset conditions are met, the iteration is stopped, and the new chromatogram at the time of stopping the iteration is used as the adjusted chromatogram.

[0009] Preferably, the number of eigenmode functions selected from the front to the back is determined according to the approximate entropy, specifically: The portion between the starting point and the end point of each peak in the chromatogram is deleted, the approximate entropy of the remaining portion of the chromatogram is calculated, and the number of eigenmode functions selected from the front to the back is determined according to the interval where the approximate entropy is located.

[0010] Preferably, the content of the pesticide to be tested is calculated using the adjusted chromatogram and the corrected mass spectrum, specifically: The content of the pesticide to be tested within the time range is calculated by the calibrated mass spectrum, and the peak area of ​​the pesticide to be tested and the area within the time range in the adjusted chromatogram are calculated; The ratio of the area within the time range to the peak area is calculated, and the content of the pesticide to be tested is calculated according to the ratio and the content of the pesticide to be tested within the time range.

[0011] In another aspect, the present invention provides a system for quantitative determination of pesticide residues, the system comprising: A determination module is used to obtain the retention time of the internal standard, use the retention time of the internal standard to calibrate the retention time of the pesticide to be tested, determine the time range for collecting the eluent according to the retention time of the internal standard and the pesticide to be tested, and after the eluent is evenly mixed, obtain the mass spectra of the internal standard and the pesticide to be tested through a mass spectrometer; A processing module, for determining the ratio of a preset peak area to an actual peak area in the chromatogram output by the detector according to the concentration of the internal standard, performing modal decomposition on the chromatogram output by the detector, gradually approaching the ratio to a target value according to the decomposition result, and obtaining an adjusted chromatogram; The content determination module is used to calibrate the mass spectrum of the pesticide to be tested using the mass spectrum information of the internal standard, and calculate the content of the pesticide to be tested using the adjusted chromatogram and the calibrated mass spectrum.

[0012] Preferably, the retention time of the pesticide to be tested is corrected using the retention time of the internal standard, specifically: Calculate the difference between the estimated retention time and the actual retention time of the internal standard; The sum of the estimated retention time of the pesticide to be tested and the difference is taken as the corrected retention time of the pesticide to be tested.

[0013] Preferably, the time range for collecting the eluate is determined according to the retention time of the internal standard and the pesticide to be tested, specifically: When the peak starting point of the internal standard or the pesticide to be tested is detected, the time interval between the peak starting point and the retention time is determined, and the time when the peak starting point passes half of the time interval is used as the starting point of the time range for collecting the eluate; The time difference between the starting point and the maximum peak height is calculated, and the maximum peak height time plus the time difference is used as the end point of the time range for collecting the eluate.

[0014] Preferably, the ratio is gradually approached to a target value according to the decomposition result, and an adjusted chromatogram is obtained, specifically: Calculate the approximate entropy of the chromatogram output by the detector, and determine the number of eigenmode functions selected from the front to the back according to the approximate entropy; Setting an adjustment coefficient for each selected intrinsic mode function, and calculating the sum of the products of all selected intrinsic mode functions and the corresponding adjustment coefficients; The chromatogram output by the detector is subtracted from the sum to obtain a new chromatogram, and the ratio of the preset peak area to the peak area of ​​the internal standard in the new chromatogram is calculated, and the adjustment coefficient is continuously adjusted to gradually approach the target value. When the preset conditions are met, the iteration is stopped, and the new chromatogram at the time of stopping the iteration is used as the adjusted chromatogram.

[0015] Preferably, the number of eigenmode functions selected from the front to the back is determined according to the approximate entropy, specifically: The portion between the starting point and the end point of each peak in the chromatogram is deleted, the approximate entropy of the remaining portion of the chromatogram is calculated, and the number of eigenmode functions selected from the front to the back is determined according to the interval where the approximate entropy is located.

[0016] Preferably, the content of the pesticide to be tested is calculated using the adjusted chromatogram and the corrected mass spectrum, specifically: The content of the pesticide to be tested within the time range is calculated by the calibrated mass spectrum, and the peak area of ​​the pesticide to be tested and the area within the time range in the adjusted chromatogram are calculated; The ratio of the area within the time range to the peak area is calculated, and the content of the pesticide to be tested is calculated according to the ratio and the content of the pesticide to be tested within the time range.

[0017] The present invention determines the time range for collecting eluent according to the retention time of the internal standard substance and the pesticide to be tested, so that the collection process is concentrated in the core area of ​​the peak shape, reducing background interference, thereby obtaining more reliable quantitative results in mass spectrometry analysis. In addition, the chromatogram is optimized according to the internal standard substance and the intrinsic mode decomposition of the chromatogram, and the deviation caused by the matrix effect is better corrected. In addition, the corrected mass spectrum can provide the content of the pesticide to be tested within a specific time range, and the adjusted chromatogram provides a complete peak area and its ratio within the time range, ensuring that the calculation is not affected by peak shape offset or baseline noise. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 This is a flow chart of Embodiment 1; Figure 2 A schematic diagram of the time range for collecting the eluate; Figure 3 Schematic diagram of modal decomposition of chromatogram; Figure 4 Schematic diagram of the adjusted chromatogram. DETAILED DESCRIPTION

[0019] The following is a description of exemplary embodiments of the present disclosure in conjunction with the accompanying drawings, including various details of the embodiments of the present disclosure to facilitate understanding, which should be considered as merely exemplary. Therefore, it should be recognized by those of ordinary skill in the art that various changes and modifications may be made to the embodiments described herein without departing from the scope and spirit of the present disclosure. Similarly, for the sake of clarity and conciseness, descriptions of well-known functions and structures are omitted in the following description.

[0020] When measuring pesticide residues in samples, the mobile phase of the samples is first prepared. Sample types include fruits, vegetables, grains, water, etc. Different samples have slightly different processing methods. Taking fruit samples as an example, fresh fruit samples are cut into small pieces, a certain amount is weighed, and crushed using a blender or homogenizer under low temperature conditions, and an appropriate amount of extraction solvent, such as acetonitrile, methanol or ethyl acetate, is added. After filtering and other steps, the internal standard is added. The prepared mobile phase is injected into the HPLC system, and the compounds in the sample will enter the chromatographic column with the mobile phase. Different compounds have different retention times in the chromatographic column and will be eluted out of the chromatographic column in turn to form separation peaks. When the compounds are eluted out of the chromatographic column, the detector of the chromatographic system will record the signal intensity of each compound, thereby forming a chromatogram. When the retention time of the pesticide is reached, a mass spectrometer is used to obtain a mass spectrum.

[0021] Figure 1 A first embodiment of the present invention is shown. Figure 1 The following steps are included: S1, obtaining the retention time of the internal standard, using the retention time of the internal standard to calibrate the retention time of the pesticide to be tested, determining the time range for collecting the eluent according to the retention times of the internal standard and the pesticide to be tested, and obtaining the mass spectra of the internal standard and the pesticide to be tested by a mass spectrometer after the eluents are evenly mixed; Internal standards are used to compensate for sample loss and instrument fluctuations in analysis, improve the accuracy and consistency of quantitative results, and correct matrix effects to ensure reliable test results in complex matrices. Preferably, the retention time of the internal standard is less than the retention time of the pesticide to be tested, that is, the peak of the internal standard appears first in the chromatogram. The retention time is the time from injection to the maximum concentration.

[0022] In chromatographic analysis, the internal standard is a known compound with a stable retention time. For example, if the internal standard has a maximum value from injection to the 2.5th minute, the retention time of the internal standard is 2.5 minutes. Chromatographic conditions (such as mobile phase, flow rate, temperature, etc.) may produce slight fluctuations over time, affecting the retention time of the pesticide to be tested. This fluctuation can be corrected by the retention time of the internal standard. In an optional embodiment, the retention time of the pesticide to be tested is corrected by using the retention time of the internal standard, specifically: calculating the difference between the estimated retention time of the internal standard and the actual retention time; the estimated retention time of the pesticide to be tested and the sum of the difference are used as the corrected retention time of the pesticide to be tested. Specifically, the offset is the actual retention time of the internal standard minus the estimated retention time of the internal standard, and the corrected retention time of the pesticide to be tested is the estimated retention time of the pesticide to be tested plus the offset. For example, the estimated retention time of the internal standard is 2.5 minutes, and the actual measured retention time is 2.7 minutes, which is 0.2 minutes. The estimated retention time of the pesticide to be tested (such as imidacloprid) is 5.5 minutes, and the retention time of the pesticide to be tested after correction is 5.7 minutes.

[0023] According to the retention time after correction, determine when to collect the eluent of the pesticide to be tested and the internal standard. According to the retention time of the internal standard and the pesticide to be tested, determine the time range for collecting the eluent, and the time range for collecting the eluent of the internal standard will be obtained, and the time range for collecting the eluent of the pesticide to be tested will also be obtained. If there are multiple pesticides to be tested, each pesticide to be tested will have a time range for collecting the eluent. Since the concentrations of the internal standard and the pesticide to be tested are low near the peak starting point and the end point, in one embodiment, the eluent is collected when a certain concentration is reached, and the moment when the certain concentration is about to be reached is used as the starting point of the time range for collecting the eluent, and the eluent is no longer collected when the concentration is reduced to a certain concentration, and the moment when the certain concentration is about to be reduced is used as the end point of the time range for collecting the eluent.

[0024] In another embodiment, the time range for collecting the eluate is determined according to the retention time of the internal standard and the pesticide to be tested, specifically: When the peak starting point of the internal standard or the pesticide to be tested is detected, the time interval between the peak starting point and the retention time is determined, and the time when the peak starting point passes half of the time interval is used as the starting point of the time range for collecting the eluate; The time difference between the starting point and the maximum peak height is calculated, and the maximum peak height time plus the time difference is used as the end point of the time range for collecting the eluate.

[0025] When determining the time range of the internal standard, since the retention time of the internal standard is not corrected, the estimated retention time of the internal standard is used as the retention time when determining the time interval between the peak start and the retention time. If the time range of collecting the eluate of the pesticide to be tested is determined, the corrected retention time is used as the retention time in the time interval between the peak start and the retention time.

[0026] When the peak starting point of the pesticide to be tested is detected, the time of the peak starting point is recorded, the time interval between the peak starting point and the corrected retention time is calculated, half of the above time interval is taken, and this half of the time is added to the peak starting point time to obtain the starting point of the time range for collecting the eluent. During the elution process, the content is constantly changing, and the moment of the maximum peak height can be obtained. The moment of the maximum peak height is the actual retention time. The maximum peak height moment of the peak is found, and the time difference between the starting point and the maximum peak height moment is calculated. This time difference is added to the maximum peak height moment to obtain the end point of the time range for collecting the eluent. For example, the peak starting point is 5.2 minutes, the retention time after correction is 5.7 minutes, and the maximum peak height appears at 5.8 minutes. The time interval between the peak starting point and the corrected retention time is 0.5 minutes, and the starting point moment is 5.45 minutes; the time difference between the starting point and the maximum peak height moment is 0.35 minutes, and the maximum peak height moment plus the time difference is 6.15 minutes, that is, the end point of the time range for collecting the eluent is 6.15 minutes. Figure 2 A schematic diagram showing the time frame over which the eluate was collected.

[0027] After the collected eluents are mixed evenly, they are analyzed by a mass spectrometer to generate a mass spectrum of the internal standard and the pesticide to be tested. In one embodiment, an eluent is collected in each time range, and each eluent is analyzed by a mass spectrometer to obtain a mass spectrum of the internal standard and a mass spectrum of the pesticide to be tested. In another embodiment, the eluents collected in each time range are mixed to obtain a mixed eluent, and the mixed eluent is analyzed by a mass spectrometer to generate a mass spectrum containing the internal standard and the pesticide to be tested.

[0028] S2, determining the ratio of the preset peak area to the actual peak area in the chromatogram output by the detector according to the concentration of the internal standard, performing modal decomposition on the chromatogram output by the detector, gradually approaching the ratio to the target value according to the decomposition result, and obtaining an adjusted chromatogram; Use the known concentration of the internal standard to determine a preset peak area, that is, the peak area that should be obtained theoretically based on the concentration of the internal standard. Find the actual peak area of ​​the internal standard in the chromatogram, calculate the ratio of the preset peak area to the actual peak area, and use it to measure the signal deviation output by the detector. Use modal decomposition to decompose the chromatographic signal output by the detector, preferably using classical modal decomposition or integrated empirical modal decomposition. According to the components obtained by the modal decomposition, adjust the signal intensity of the chromatogram output by the detector to gradually approach the target ratio. After the above correction, the peak areas of the internal standard and the analyte on the chromatogram should be more consistent with the preset values, thereby generating an adjusted chromatogram. The adjusted chromatogram eliminates the deviation caused by detector drift or changes in instrument sensitivity, and improves the accuracy of the results.

[0029] In an optional embodiment, the ratio is gradually approached to a target value according to the decomposition result, and an adjusted chromatogram is obtained, specifically: Calculate the approximate entropy of the chromatogram output by the detector, and determine the number of eigenmode functions selected from the front to the back according to the approximate entropy; Setting an adjustment coefficient for each selected intrinsic mode function, and calculating the sum of the products of all selected intrinsic mode functions and the corresponding adjustment coefficients; The chromatogram output by the detector is subtracted from the sum to obtain a new chromatogram, and the ratio of the preset peak area to the peak area of ​​the internal standard in the new chromatogram is calculated, and the adjustment coefficient is continuously adjusted to gradually approach the target value. When the preset conditions are met, the iteration is stopped, and the new chromatogram at the time of stopping the iteration is used as the adjusted chromatogram.

[0030] The greater the noise, the higher the approximate entropy. After modal decomposition of the chromatogram, multiple intrinsic mode functions (IMFs) are obtained. According to the value of the approximate entropy, the number of intrinsic mode functions is selected from the front to the back.

[0031] Each IMF represents a pattern of different frequencies and characteristics in the chromatogram. The smaller the number of the IMF component, the higher the frequency component, which often contains more noise components. Figure 3 A schematic diagram of modal decomposition of a chromatogram is shown. In an optional embodiment, the number of eigenmode functions selected from the front to the back is determined based on the approximate entropy, specifically: The portion between the starting point and the end point of each peak in the chromatogram is deleted, the approximate entropy of the remaining portion of the chromatogram is calculated, and the number of eigenmode functions selected from the front to the back is determined according to the interval where the approximate entropy is located.

[0032] In the chromatogram, find the starting point and end point of each peak, and delete the signal within the range, leaving only the background noise and other peak-free areas. Calculate the approximate entropy of the chromatogram data after deleting the peak area. After removing the peak, the approximate entropy can more truly reflect the complexity of the background noise. The approximate entropy is divided into several intervals, each interval corresponding to a different number of IMFs. For example, the low approximate entropy interval selects fewer IMF components to retain the main signal, the medium approximate entropy interval selects an appropriate amount of IMF components to achieve balance, and the high approximate entropy interval selects more IMF components to separate noise. In a more specific embodiment, the number of intrinsic mode functions corresponding to the low approximate entropy interval is 1, the number of intrinsic mode functions corresponding to the medium approximate entropy interval is 2, and the number of intrinsic mode functions corresponding to the medium approximate entropy interval is 3 or 4.

[0033] The intrinsic mode functions are sorted in ascending order according to the serial numbers of the IMF components, and the IMF components of the aforementioned number of intrinsic mode functions are selected. For example, if the approximate entropy is in the middle approximate entropy interval, the number of intrinsic mode functions selected from the front to the back is determined to be 2, and IMF1 and IMF2 are selected.

[0034] Assign an adjustment coefficient to each IMF, and optimize the chromatogram by adjusting these coefficients. The adjustment coefficient is used to amplify or reduce the intensity of the IMF to correct the amplitude deviation of the signal. Multiply each selected IMF with its corresponding adjustment coefficient, and accumulate all the products. Subtract the above calculated accumulation from the original chromatogram output by the detector to obtain a new chromatogram. This process is used to remove some noise or deviation from the original signal in order to correct the signal. Calculate the ratio of the preset peak area, that is, the theoretical peak area of ​​the internal standard, to the actual peak area of ​​the internal standard in the new chromatogram, and adjust the adjustment coefficient of the selected IMF so that the actual peak area of ​​the internal standard gradually approaches the preset peak area. Continuously adjust the adjustment coefficient and repeat the above steps to gradually approach the preset target ratio. When the ratio reaches the accuracy requirement, stop the iteration and use the chromatogram obtained at this time as the final adjusted chromatogram. Among them, the target value is 1.

[0035] Since each intrinsic mode function has an adjustment coefficient, in order to avoid the uncertainty that may be caused by selecting the IMF component, in another optional embodiment, the ratio is gradually approached to the target value according to the decomposition result, and an adjusted chromatogram is obtained, specifically: An adjustment coefficient is set for each intrinsic mode function, and the sum of the products of all intrinsic mode functions and the corresponding adjustment coefficient is calculated; The chromatogram output by the detector is subtracted from the sum to obtain a new chromatogram, and the ratio of the preset peak area to the peak area of ​​the internal standard in the new chromatogram is calculated, and the adjustment coefficient is continuously adjusted to gradually approach the target value. When the preset conditions are met, the iteration is stopped, and the new chromatogram at the time of stopping the iteration is used as the adjusted chromatogram. Figure 4 The adjusted chromatogram is shown.

[0036] S3, using the mass spectrum information of the internal standard to calibrate the mass spectrum of the pesticide to be tested, and using the adjusted chromatogram and the calibrated mass spectrum to calculate the content of the pesticide to be tested.

[0037] As mentioned above, there are two forms of mass spectra. The first form is to perform mass spectrometry analysis on the internal standard and each pesticide to be tested, respectively. The internal standard corresponds to a mass spectrometry, and each pesticide to be tested corresponds to a mass spectrometry. The second form is to perform mass spectrometry analysis on the mixture of the internal standard and the eluent of all the pesticides to be tested, and obtain a mass spectrometry containing the internal standard and each pesticide to be tested. Both forms use the mass spectrum information of the internal standard to calibrate the mass spectrum of the pesticide to be tested. In one embodiment, the ratio of the theoretical peak value to the actual peak value of the internal standard in the mass spectrum is obtained, and the ratio is multiplied by the mass spectrum of the pesticide to be tested, and the mass spectrum after the product is used as the mass spectrum after calibration.

[0038] In an optional embodiment, the content of the pesticide to be tested is calculated using the adjusted chromatogram and the corrected mass spectrum, specifically: The content of the pesticide to be tested within the time range is calculated by the calibrated mass spectrum, and the peak area of ​​the pesticide to be tested and the area within the time range in the adjusted chromatogram are calculated; The ratio of the area within the time range to the peak area is calculated, and the content of the pesticide to be tested is calculated according to the ratio and the content of the pesticide to be tested within the time range.

[0039] On the adjusted mass spectrum, select the characteristic ion of the pesticide to be tested, calculate the peak area or peak height of the characteristic ion within the specified time range, and then obtain the content of the pesticide to be tested within the time range. On the adjusted chromatogram, find the complete peak area of ​​the pesticide to be tested, and calculate the total peak area of ​​the area, that is, the overall peak area of ​​the pesticide to be tested. At the same time, calculate the area within the time range in the adjusted chromatogram, which is a subset of the total peak area. Calculate the ratio of the area within the time range to the complete peak area, and according to the above ratio, to obtain the content of the pesticide to be tested, more specifically, divide the content within the time range by the ratio to obtain the content of the pesticide to be tested. For example, the content of the pesticide to be tested measured in the time range of the calibrated mass spectrum is 50, the complete peak area of ​​the pesticide to be tested in the adjusted chromatogram is 1000, the peak area within the time range is 200, the ratio is 0.2, and the content of the pesticide to be tested is 250.

[0040] In another optional embodiment, the content of the pesticide to be tested is calculated using the adjusted chromatogram and the corrected mass spectrum, specifically: Calculating the ratio of the peak area of ​​the pesticide to be tested to the peak area of ​​the internal standard in the adjusted chromatogram, and taking the product of the concentration of the internal standard and the ratio as the content of the pesticide to be tested in the chromatogram; Calculate the ratio of the characteristic peak intensities of the pesticide to be tested and the internal standard in the mass spectrum after correction, and use the product of the concentration of the internal standard and the ratio as the content of the pesticide to be tested in the mass spectrum; The average value of the content of the pesticide to be tested in the chromatogram and the content of the pesticide to be tested in the mass spectrum is taken as the content of the pesticide to be tested.

[0041] In another aspect, the present invention provides a system for quantitative determination of pesticide residues, the system comprising: A determination module is used to obtain the retention time of the internal standard, use the retention time of the internal standard to calibrate the retention time of the pesticide to be tested, determine the time range for collecting the eluent according to the retention time of the internal standard and the pesticide to be tested, and after the eluent is evenly mixed, obtain the mass spectra of the internal standard and the pesticide to be tested through a mass spectrometer; A processing module, for determining the ratio of a preset peak area to an actual peak area in the chromatogram output by the detector according to the concentration of the internal standard, performing modal decomposition on the chromatogram output by the detector, gradually approaching the ratio to a target value according to the decomposition result, and obtaining an adjusted chromatogram; The content determination module is used to calibrate the mass spectrum of the pesticide to be tested using the mass spectrum information of the internal standard, and calculate the content of the pesticide to be tested using the adjusted chromatogram and the calibrated mass spectrum.

[0042] Preferably, the retention time of the pesticide to be tested is corrected using the retention time of the internal standard, specifically: Calculate the difference between the estimated retention time and the actual retention time of the internal standard; The sum of the estimated retention time of the pesticide to be tested and the difference is taken as the corrected retention time of the pesticide to be tested.

[0043] Preferably, the time range for collecting the eluate is determined according to the retention time of the internal standard and the pesticide to be tested, specifically: When the peak starting point of the internal standard or the pesticide to be tested is detected, the time interval between the peak starting point and the retention time is determined, and the time when the peak starting point passes half of the time interval is used as the starting point of the time range for collecting the eluate; The time difference between the starting point and the maximum peak height is calculated, and the maximum peak height time plus the time difference is used as the end point of the time range for collecting the eluate.

[0044] Preferably, the ratio is gradually approached to a target value according to the decomposition result, and an adjusted chromatogram is obtained, specifically: Calculate the approximate entropy of the chromatogram output by the detector, and determine the number of eigenmode functions selected from the front to the back according to the approximate entropy; Setting an adjustment coefficient for each selected intrinsic mode function, and calculating the sum of the products of all selected intrinsic mode functions and the corresponding adjustment coefficients; The chromatogram output by the detector is subtracted from the sum to obtain a new chromatogram, and the ratio of the preset peak area to the peak area of ​​the internal standard in the new chromatogram is calculated, and the adjustment coefficient is continuously adjusted to gradually approach the target value. When the preset conditions are met, the iteration is stopped, and the new chromatogram at the time of stopping the iteration is used as the adjusted chromatogram.

[0045] Preferably, the number of eigenmode functions selected from the front to the back is determined according to the approximate entropy, specifically: The portion between the starting point and the end point of each peak in the chromatogram is deleted, the approximate entropy of the remaining portion of the chromatogram is calculated, and the number of eigenmode functions selected from the front to the back is determined according to the interval where the approximate entropy is located.

[0046] Preferably, the content of the pesticide to be tested is calculated using the adjusted chromatogram and the corrected mass spectrum, specifically: The content of the pesticide to be tested within the time range is calculated by the calibrated mass spectrum, and the peak area of ​​the pesticide to be tested and the area within the time range in the adjusted chromatogram are calculated; The ratio of the area within the time range to the peak area is calculated, and the content of the pesticide to be tested is calculated according to the ratio and the content of the pesticide to be tested within the time range.

[0047] Finally, the present invention also provides a computer-readable storage medium or a computer-readable program, wherein the computer-readable program is stored on the readable storage medium, and when the computer-readable program is executed by a processor, the method described in the first embodiment is implemented.

[0048] The program code for implementing the method of the present disclosure may be written in any combination of one or more programming languages. These program codes may be provided to a processor or controller of a general-purpose computer, a special-purpose computer, or other programmable data processing device, so that the program code, when executed by the processor or controller, enables the functions / operations specified in the flow chart and / or block diagram to be implemented. The program code may be executed entirely on the machine, partially on the machine, partially on the machine and partially on a remote machine as a stand-alone software package, or entirely on a remote machine or server.

Claims

1. A method for quantitative determination of pesticide residues, characterized in that: The method comprises: Obtaining the retention time of the internal standard, using the retention time of the internal standard to calibrate the retention time of the pesticide to be tested, determining the time range for collecting the eluent according to the retention times of the internal standard and the pesticide to be tested, and obtaining the mass spectra of the internal standard and the pesticide to be tested by a mass spectrometer after the eluents are evenly mixed; Determine the ratio of the preset peak area to the actual peak area in the chromatogram output by the detector according to the concentration of the internal standard, perform modal decomposition on the chromatogram output by the detector, gradually approach the ratio to the target value according to the decomposition result, and obtain an adjusted chromatogram; The mass spectrum of the pesticide to be tested is corrected using the mass spectrum information of the internal standard, and the content of the pesticide to be tested is calculated using the adjusted chromatogram and the corrected mass spectrum.

2. The method according to claim 1, characterized in that The retention time of the pesticide to be tested is corrected by using the retention time of the internal standard, specifically: Calculate the difference between the estimated retention time and the actual retention time of the internal standard; The sum of the estimated retention time of the pesticide to be tested and the difference is taken as the corrected retention time of the pesticide to be tested.

3. The method according to claim 1, characterized in that The time range for collecting the eluate is determined according to the retention time of the internal standard and the pesticide to be tested, specifically: When the peak starting point of the internal standard or the pesticide to be tested is detected, the time interval between the peak starting point and the retention time is determined, and the time when the peak starting point passes half of the time interval is used as the starting point of the time range for collecting the eluate; The time difference between the starting point and the maximum peak height is calculated, and the maximum peak height time plus the time difference is used as the end point of the time range for collecting the eluate.

4. The method according to claim 1, characterized in that The ratio is gradually approached to the target value according to the decomposition result, and an adjusted chromatogram is obtained, specifically: Calculate the approximate entropy of the chromatogram output by the detector, and determine the number of eigenmode functions selected from the front to the back according to the approximate entropy; Setting an adjustment coefficient for each selected intrinsic mode function, and calculating the sum of the products of all selected intrinsic mode functions and the corresponding adjustment coefficients; The chromatogram output by the detector is subtracted from the sum to obtain a new chromatogram, and the ratio of the preset peak area to the peak area of ​​the internal standard in the new chromatogram is calculated, and the adjustment coefficient is continuously adjusted to gradually approach the target value. When the preset conditions are met, the iteration is stopped, and the new chromatogram at the time of stopping the iteration is used as the adjusted chromatogram.

5. The method according to claim 4, characterized in that The number of eigenmode functions selected from the front to the back is determined according to the approximate entropy, specifically: The portion between the starting point and the end point of each peak in the chromatogram is deleted, the approximate entropy of the remaining portion of the chromatogram is calculated, and the number of eigenmode functions selected from the front to the back is determined according to the interval where the approximate entropy is located.

6. The method according to claim 1, characterized in that The content of the pesticide to be tested is calculated using the adjusted chromatogram and the calibrated mass spectrum, specifically: The content of the pesticide to be tested within the time range is calculated by the calibrated mass spectrum, and the peak area of ​​the pesticide to be tested and the area within the time range in the adjusted chromatogram are calculated; The ratio of the area within the time range to the peak area is calculated, and the content of the pesticide to be tested is calculated according to the ratio and the content of the pesticide to be tested within the time range.

7. A pesticide residue quantitative determination system, characterized in that: The system comprises: A determination module is used to obtain the retention time of the internal standard, use the retention time of the internal standard to calibrate the retention time of the pesticide to be tested, determine the time range for collecting the eluent according to the retention time of the internal standard and the pesticide to be tested, and after the eluent is evenly mixed, obtain the mass spectra of the internal standard and the pesticide to be tested through a mass spectrometer; A processing module, for determining the ratio of a preset peak area to an actual peak area in the chromatogram output by the detector according to the concentration of the internal standard, performing modal decomposition on the chromatogram output by the detector, gradually approaching the ratio to a target value according to the decomposition result, and obtaining an adjusted chromatogram; The content determination module is used to calibrate the mass spectrum of the pesticide to be tested using the mass spectrum information of the internal standard, and calculate the content of the pesticide to be tested using the adjusted chromatogram and the calibrated mass spectrum.

8. The system according to claim 7, characterized in that The time range for collecting the eluate is determined according to the retention time of the internal standard and the pesticide to be tested, specifically: When the peak starting point of the internal standard or the pesticide to be tested is detected, the time interval between the peak starting point and the retention time is determined, and the time when the peak starting point passes half of the time interval is used as the starting point of the time range for collecting the eluate; The time difference between the starting point and the maximum peak height is calculated, and the maximum peak height time plus the time difference is used as the end point of the time range for collecting the eluate.

9. The system according to claim 7, characterized in that The ratio is gradually approached to the target value according to the decomposition result, and an adjusted chromatogram is obtained, specifically: Calculate the approximate entropy of the chromatogram output by the detector, and determine the number of eigenmode functions selected from the front to the back according to the approximate entropy; Setting an adjustment coefficient for each selected intrinsic mode function, and calculating the sum of the products of all selected intrinsic mode functions and the corresponding adjustment coefficients; The chromatogram output by the detector is subtracted from the sum to obtain a new chromatogram, and the ratio of the preset peak area to the peak area of ​​the internal standard in the new chromatogram is calculated, and the adjustment coefficient is continuously adjusted to gradually approach the target value. When the preset conditions are met, the iteration is stopped, and the new chromatogram at the time of stopping the iteration is used as the adjusted chromatogram.

10. A computer program, characterized in that When the computer program is executed by a processor, the computer program implements the method according to any one of claims 1 to 6.

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