A method for detecting nitrobenzene compounds in aquatic products
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-05-15
- Publication Date
- 2026-08-11
AI Technical Summary
[0003]水产品基质成分复杂，富含脂肪、蛋白质、色素等内源性干扰物质，极易对硝基苯类化合物的提取、净化及检测造成干扰，引发基质效应，导致检测结果偏差；现有水产品中硝基苯类化合物检测方法普遍存在提取效率不均衡、净化流程繁琐、基质干扰去除不彻底、色谱分离效果差、定性定量准确性不足等问题，无法实现多种硝基苯类化合物同步、快速、灵敏的检测，难以满足水产品中硝基苯类化合物高通量、高精度的检测需求
1.针对水产品复杂基质特性，采用超声辅助提取提升硝基苯类化合物提取效率，结合固相萃取与无水干燥联用净化工艺，高效去除脂肪、蛋白质等基质干扰，避免目标物损失，大幅降低基质效应对检测的干扰。
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Figure CN122545700A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of aquatic product safety testing technology, specifically to a method for detecting nitrobenzene compounds in aquatic products. Background Technology
[0002] Nitrobenzene compounds are a class of persistent organic pollutants that are highly toxic, difficult to degrade, and have strong bioaccumulation properties. They are widely present in the aquatic environment and can accumulate in aquatic products through the aquatic food chain. Long-term human consumption of aquatic products containing these pollutants can damage the liver, blood, and central nervous system. Some nitrobenzene compounds have been listed as potential carcinogens. Therefore, accurate detection of nitrobenzene compounds in aquatic products is of great significance for food safety.
[0003] The matrix composition of aquatic products is complex, rich in endogenous interfering substances such as fats, proteins, and pigments, which can easily interfere with the extraction, purification, and detection of nitrobenzene compounds, causing matrix effects and leading to deviations in detection results. Existing methods for detecting nitrobenzene compounds in aquatic products generally suffer from problems such as uneven extraction efficiency, cumbersome purification processes, incomplete removal of matrix interference, poor chromatographic separation, and insufficient qualitative and quantitative accuracy. They cannot achieve simultaneous, rapid, and sensitive detection of multiple nitrobenzene compounds, and cannot meet the high-throughput and high-precision detection requirements of nitrobenzene compounds in aquatic products.
[0004] To address the aforementioned shortcomings of existing detection technologies, this invention proposes a method for detecting nitrobenzene compounds in aquatic products. Summary of the Invention
[0005] To solve the above-mentioned technical problems, a method for detecting nitrobenzene compounds in aquatic products is provided. This technical solution solves the above-mentioned problems.
[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows:
[0007] A method for detecting nitrobenzene compounds in aquatic products includes:
[0008] The aquatic product samples to be tested were homogenized and crushed, and after adding the extraction solvent, ultrasonic-assisted extraction was performed, followed by centrifugation to obtain the primary extract.
[0009] The primary extract was purified and concentrated by a combination of solid-phase extraction and anhydrous drying to remove interference from fat and protein matrices, and the sample solution to be tested was prepared.
[0010] The sample solution was injected into a gas chromatograph-mass spectrometer, and the characteristic signals of nitrobenzene compounds were collected by temperature-programmed chromatographic separation and selected ion monitoring mode.
[0011] The retention time and characteristic ion abundance ratio of the sample are compared with the data of the standard to complete the qualitative determination of nitrobenzene compounds;
[0012] The content of nitrobenzene compounds in the sample was calculated based on the peak area of characteristic ions using the matrix-matched standard curve method.
[0013] The validity of the final test data is determined by verifying the test results through spiked recovery and parallel experiments.
[0014] Preferably, the aquatic product sample to be tested is homogenized and crushed, then extracted with an extraction solvent using ultrasound-assisted extraction, followed by centrifugation to obtain a primary extract, comprising:
[0015] Weigh the homogenized aquatic product sample, add dichloromethane-based extraction solvent, mix by high-speed vortexing, and then extract by constant-temperature ultrasonic extraction.
[0016] The mixture is centrifuged at high speed, and the supernatant obtained is the primary extract.
[0017] Preferably, the primary extract is purified and concentrated using a combination of solid-phase extraction and anhydrous drying to remove interference from lipid and protein matrices, resulting in the sample test solution, comprising:
[0018] Anhydrous desiccant was added to the primary extract to dehydrate it, and the solid desiccant was removed by filtration and then concentrated by nitrogen blowing.
[0019] The concentrate was purified by an activated solid-phase extraction column, the target analyte was eluted and the volume was adjusted to obtain the sample solution to be tested.
[0020] Preferably, the sample solution is injected into a gas chromatograph-mass spectrometer, and characteristic signals of nitrobenzene compounds are acquired through temperature-programmed chromatographic separation and selected ion monitoring mode, including:
[0021] A capillary column was used, and chromatographic separation was completed by setting the injection port temperature and the programmed temperature gradient.
[0022] An electron impact ion source was used, and the characteristic quantitative and qualitative ion peak areas of nitrobenzene compounds were collected using the selected ion monitoring mode.
[0023] Preferably, the retention time and characteristic ion abundance ratio of the sample are compared with the data of the standard to complete the qualitative determination of nitrobenzene compounds, including:
[0024] Compare the consistency of chromatographic retention times between the sample and the standard;
[0025] When the deviations in the abundance ratios of characteristic ions between the sample and the standard both meet the standard requirements, the corresponding nitrobenzene compound is determined to be detected.
[0026] Preferably, the matrix-matched standard curve method is used to calculate the content of nitrobenzene compounds in the sample based on the characteristic ion peak area, including:
[0027] Prepare a series of standard working solutions with concentrations matching the sample matrix, and plot a concentration-peak area standard curve;
[0028] Substitute the characteristic ion peak area of the sample into the standard curve, and calculate the actual content of nitrobenzene compounds in aquatic products by combining the pretreatment dilution factor.
[0029] Preferably, the validity of the final test data is determined by verifying the test results through spiked recovery and parallel experiments, including:
[0030] Perform spiked recovery tests on blank samples and calculate the method recovery rate;
[0031] Perform multiple parallel tests on the same sample and calculate the method precision.
[0032] The test results are considered valid when both the recovery rate and precision are within the preset acceptable range.
[0033] Preferably, the concentrate is purified by an activated solid-phase extraction column, the target analyte is eluted, and the volume is adjusted, including:
[0034] The solid-phase extraction column was activated and eluted sequentially with organic solvents;
[0035] After the concentrated solution is loaded with the adsorption solution, the target analyte is eluted with an eluent, the eluent is collected and concentrated by nitrogen blowing, and then an organic solvent is added to make up to a fixed volume.
[0036] Preferably, a capillary column is used, and chromatographic separation is completed by setting the injection port temperature and the programmed temperature gradient, including:
[0037] An inert capillary column was used, and the injection port temperature and constant carrier gas flow rate were set.
[0038] By setting the initial column temperature, heating rate, and termination column temperature, the complete separation of nitrobenzene compounds can be achieved.
[0039] Preferably, the nitrobenzene compounds include one or more of nitrobenzene, o-nitrotoluene, m-nitrotoluene, p-nitrotoluene, and 2,4-dinitrotoluene.
[0040] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. To address the complex matrix characteristics of aquatic products, ultrasonic-assisted extraction is employed to improve the extraction efficiency of nitrobenzene compounds. Combined with a purification process of solid-phase extraction and anhydrous drying, matrix interference such as fats and proteins is efficiently removed, avoiding the loss of target substances and significantly reducing the interference of matrix effects on detection.
[0041] 2. By combining programmed temperature chromatography with selected ion monitoring mode, a variety of nitrobenzene compounds can be separated efficiently and acquired with high sensitivity. The dual-dimensional qualitative determination using retention time and characteristic ion abundance ratio effectively avoids false positive results and significantly improves the accuracy of qualitative detection.
[0042] 3. The matrix matching standard curve method is used for quantification, which accurately offsets the quantitative deviation caused by the aquatic product matrix. Combined with spiked recovery and parallel test dual verification, it ensures that the recovery rate, precision and sensitivity of the detection method meet the food safety testing standards, and the quantitative results are accurate and reliable.
[0043] 4. The detection method is simple to operate and efficient, and can simultaneously realize the qualitative and quantitative detection of multiple nitrobenzene compounds in aquatic products. It has a wide range of applications and provides a stable and reliable technical solution for the rapid, sensitive and accurate detection of nitrobenzene compounds in aquatic products. Attached Figure Description
[0044] Figure 1 This is a flowchart illustrating the steps of the present invention. Detailed Implementation
[0045] The following description is intended to disclose the invention and enable those skilled in the art to implement it. The preferred embodiments described below are merely examples, and other obvious variations will occur to those skilled in the art.
[0046] Reference Figure 1 As shown, a method for detecting nitrobenzene compounds in aquatic products includes:
[0047] S1, homogenize and crush the aquatic product sample to be tested, add extraction solvent and extract with ultrasonic assistance, and centrifuge to obtain primary extract;
[0048] S2, the primary extract was purified and concentrated by a combination of solid phase extraction and anhydrous drying to remove interference from fat and protein matrices and obtain the sample solution to be tested.
[0049] S3, inject the sample solution into the gas chromatograph-mass spectrometer, and collect the characteristic signals of nitrobenzene compounds through temperature-programmed chromatographic separation and selected ion monitoring mode;
[0050] S4. Compare the retention time and characteristic ion abundance ratio of the sample with the standard data to complete the qualitative determination of nitrobenzene compounds.
[0051] S5, the matrix-matched standard curve method was used to calculate the content of nitrobenzene compounds in the sample based on the peak area of characteristic ions;
[0052] S6. The validity of the final test data is determined by verifying the test results through spiked recovery and parallel tests.
[0053] The matrix composition of aquatic products is highly complex, rich in endogenous interfering substances such as fats, proteins, pigments, and phospholipids. Nitrobenzene compounds, with their low residual levels and fat-soluble characteristics, readily bind to matrix components. Traditional detection methods suffer from insufficient target analyte extraction, incomplete removal of matrix interference, poor chromatographic separation, false positives in qualitative determination, and significant deviations in quantitative results due to matrix effects, failing to achieve sensitive, accurate, and stable detection of nitrobenzene compounds in aquatic products. This invention optimizes the entire process—pretreatment, separation, qualitative analysis, quantification, and validation—fundamentally resolving the contradiction between matrix interference and detection accuracy, thus meeting the technical requirements for residual nitrobenzene compounds in aquatic products.
[0054] In some embodiments, the aquatic product sample to be tested is homogenized and crushed, an extraction solvent is added, and ultrasonic-assisted extraction is performed. The primary extract is obtained by centrifugation. The process includes: weighing the homogenized aquatic product sample, adding a dichloromethane-based extraction solvent, vortexing at high speed, and then performing ultrasonic extraction at a constant temperature; centrifuging the mixture at high speed, and separating the supernatant, which is the primary extract.
[0055] The homogenization process involves breaking the aquatic product tissue into a uniform and fine homogenate to increase the contact area between the target substance and the extraction solvent. The ultrasonic-assisted extraction utilizes ultrasonic cavitation to disrupt the sample matrix structure and accelerate the transfer of nitrobenzene compounds into the solvent. The primary extract is a crude extract containing nitrobenzene compounds and some matrix impurities.
[0056] Specifically, after removing impurities from edible aquatic product tissues, they are placed in a homogenizer and thoroughly broken down until no obvious particles remain. A precise amount of homogenized sample is then placed in a centrifuge tube. A dichloromethane extraction solvent, appropriately proportioned to the sample, is added and mixed at high speed using a vortex mixer to ensure complete contact between the solvent and the sample. The mixture is then placed in a constant-temperature ultrasonic cleaner for ultrasonic extraction at a constant temperature. The cavitation and mechanical effects generated by ultrasonic vibration disrupt the cell structure of the aquatic product, eluting nitrobenzene compounds bound to the tissue into the extraction solvent. After extraction, the centrifuge tubes are placed in a high-speed centrifuge and centrifuged at a constant speed to separate the solid residue from the liquid extract. The clear liquid at the top is then collected as the primary extract containing the target compound.
[0057] This step optimizes the extraction method based on the tissue characteristics of aquatic product matrix, adopting a homogenization combined with ultrasound-assisted extraction mode, which significantly improves the extraction efficiency of nitrobenzene compounds and solves the problem of insufficient dissolution of target substances in traditional extraction methods, providing a sufficient basis for subsequent detection.
[0058] In some embodiments, a combination of solid-phase extraction and anhydrous drying is used to purify and concentrate the primary extract to remove interference from fat and protein matrices, thereby obtaining the sample test solution. This includes: adding anhydrous desiccant to the primary extract for dehydration, filtering to remove the solid desiccant, and then concentrating with nitrogen blowing; purifying the concentrate using an activated solid-phase extraction column, eluting the target analyte, and adjusting the volume to obtain the sample test solution.
[0059] The anhydrous drying process utilizes an anhydrous desiccant to remove residual moisture from the extract, preventing moisture from interfering with subsequent purification and detection. The solid-phase extraction process uses a solid-phase adsorbent to selectively adsorb the target analyte and exclude matrix impurities. The sample solution is a pure solution that has been free of all interferences and can be directly injected for analysis.
[0060] Specifically, sufficient anhydrous desiccant is added to the primary extract, and the mixture is slowly shaken and allowed to stand to allow the desiccant to fully adsorb the residual water in the extract, eliminating the interference of water on the separation of nitrobenzene compounds. The solid desiccant is removed by filtration to obtain anhydrous extract. The dehydrated extract is placed in a nitrogen evaporator, and an inert gas is introduced at a constant flow rate. Under constant temperature conditions, the solvent is slowly blown to near dryness to achieve concentration and enrichment of the target analytes. The solid-phase extraction column is activated and eluted with organic solvents to achieve the optimal adsorption state of the adsorbent. The concentrated solution is then loaded onto the solid-phase extraction column, allowing the target analytes to be specifically adsorbed by the adsorbent, while large molecular impurities such as fats and proteins flow out with the waste liquid. The nitrobenzene compounds adsorbed on the column are then completely eluted with an eluent. All eluent is collected and concentrated again by nitrogen evaporation. A final volume solvent is added and mixed to obtain a sample solution free of matrix interference.
[0061] This step employs a dual purification mode combining anhydrous drying and solid-phase extraction to remove various matrix interferences such as water, fat, and protein in layers, avoiding contamination of the chromatographic column and detector by impurities. At the same time, it achieves concentration and enrichment of the target analyte, significantly reducing matrix effects and improving detection sensitivity.
[0062] In some embodiments, the sample solution is injected into a gas chromatograph-mass spectrometer, and characteristic signals of nitrobenzene compounds are acquired through temperature-programmed chromatography and selected ion monitoring mode. This includes: using an inert capillary column, setting the injection port temperature and a constant carrier gas flow rate; setting temperature-programmed parameters for initial column temperature, heating rate, and termination column temperature to achieve complete separation of nitrobenzene compounds; and using an electron impact ion source and selected ion monitoring mode to acquire the characteristic quantitative and qualitative ion peak areas of nitrobenzene compounds.
[0063] The temperature-programmed chromatography separation achieves complete baseline separation of nitrobenzene compounds with different structures through gradient temperature increase. The selected ion monitoring mode is a detection mode that collects only the characteristic ion signals of the target analyte. The peak area of the characteristic ion is the core signal data used for quantitative calculation.
[0064] Specifically, a high-temperature resistant and inert capillary column was selected as the separation carrier. A stable injection port temperature and a constant flow rate of inert carrier gas were set to ensure the stability of sample injection. To address the boiling point differences between nitrobenzene and nitrotoluene compounds, segmented temperature programming parameters were set. Low-temperature holding allowed for the separation of low-boiling-point components, medium-speed heating achieved the separation of medium-boiling-point components, and high-temperature holding completed the elution of high-boiling-point components, ensuring complete separation of multiple nitrobenzene compounds without peak overlap or tailing. The electron impact ion source of the gas chromatography-mass spectrometry (GC-MS) was activated to ionize the separated nitrobenzene compound molecules. Ion monitoring mode was selected to collect only the characteristic qualitative and quantitative ions corresponding to each nitrobenzene compound, shielding against ion signal interference from matrix impurities and accurately acquiring the characteristic ion peak area signals of the target analytes.
[0065] This step achieves efficient separation of multi-component target analytes through programmed temperature rise. Combined with the specific acquisition of selected ion monitoring mode, matrix interference is shielded from both the separation and detection stages, significantly improving the specificity and sensitivity of the signal and solving the problem of target analyte signals being easily masked in complex matrices.
[0066] In some embodiments, the retention time and characteristic ion abundance ratio of the sample are compared with the data of the standard to complete the qualitative determination of nitrobenzene compounds, including: comparing the consistency of the chromatographic retention time of the sample and the standard; and determining the detection of the corresponding nitrobenzene compound when the deviation of the characteristic ion abundance ratio of the sample and the standard both meet the standard requirements.
[0067] The retention time is the elution time of the target analyte in the chromatographic column, which is the core basis for qualitative identification. The characteristic ion abundance ratio is the ratio of the signal intensity of the characteristic quantitative ion to the qualitative ion, which is a key indicator for eliminating false positives.
[0068] Specifically, the chromatographic retention time of nitrobenzene compound standards under the same detection conditions is used as a qualitative benchmark. The deviation between the retention time of the chromatographic peak in the sample and the retention time of the standard is compared. If the deviation is within the allowable range, the retention time is considered to be matched. The signal intensities of the characteristic quantitative ions and qualitative ions of the target compound in the sample are extracted, and their abundance ratio is calculated and compared with the abundance ratio of the characteristic ions of the standard. The deviation of the abundance ratio is within the allowable range of the national standard. Only when both the retention time and the characteristic ion abundance ratio are matched can the corresponding nitrobenzene compound be detected in the sample. If either condition is not matched, it is considered not detected.
[0069] This step employs a dual-dimensional qualitative determination based on retention time and characteristic ion abundance ratio, completely avoiding false positives caused by matrix impurity peaks and improving the accuracy and reliability of the qualitative results.
[0070] In some embodiments, the matrix-matched standard curve method is used to calculate the content of nitrobenzene compounds in the sample based on the peak area of characteristic ions. This includes: preparing a series of standard working solutions with concentrations matched to the sample matrix and plotting a concentration-peak area standard curve; substituting the peak area of the characteristic ions of the sample into the standard curve and calculating the actual content of nitrobenzene compounds in the aquatic product based on the pretreatment dilution factor.
[0071] The matrix-matched standard curve is a curve plotted using a standard solution prepared with a blank matrix extract, which can completely offset the interference of matrix effect on quantitative results. The dilution factor is the total conversion factor of extraction, concentration and volume adjustment in the pretreatment process.
[0072] Specifically, a blank aquatic product matrix of the same type as the test sample was selected, and a blank matrix extract was prepared using the same pretreatment method. A series of standard working solutions of nitrobenzene compounds with different concentration gradients were prepared using the blank matrix extract. These solutions were then detected by gas chromatography-mass spectrometry (GC-MS). A linear standard curve was plotted with the concentration of the standard working solution on the x-axis and the corresponding characteristic ion peak area on the y-axis to ensure a good linear relationship. The characteristic ion peak area of the test sample was substituted into the standard curve to calculate the concentration of nitrobenzene compounds in the test sample. The total dilution factor was calculated by combining parameters such as the sample mass, extraction solvent volume, and concentration volume, and finally, the actual residual content of nitrobenzene compounds in the aquatic product was obtained.
[0073] This step uses the matrix matching standard curve method for quantification, which accurately offsets the quantitative deviation caused by the aquatic product matrix, solves the problem of inaccurate quantitative results from traditional solvent standard curves, and ensures the accuracy and authenticity of the quantitative results.
[0074] In some embodiments, the validity of the final test data is determined by verifying the test results through spiked recovery and parallel tests, including: performing a spiked recovery test on a blank sample and calculating the method recovery rate; performing multiple parallel tests on the same sample and calculating the method precision; and determining the test results to be valid when both the recovery rate and precision are within the preset acceptable range.
[0075] The spiked recovery test involves adding a known amount of standard to a blank sample and detecting the recovery amount to verify the accuracy of the method. The parallel test involves testing the same sample multiple times to verify the repeatability and stability of the method.
[0076] Specifically, blank aquatic product samples were selected and divided into two groups. One group was supplemented with nitrobenzene compound standards at low, medium, and high concentrations, while the other group served as a blank control. The same pretreatment and detection steps were followed to complete the experiment. The ratio of the measured content to the theoretical amount of the spiked sample was calculated to obtain the method recovery rate. Multiple test solutions were prepared in parallel from the same aquatic product sample and tested multiple times under the same detection conditions. The relative standard deviation of the multiple test results was calculated to obtain the method precision. According to food safety testing standards, if both the recovery rate and the relative standard deviation are within the preset acceptable range, the test results are deemed valid and can be used as the final test data. If any indicator fails to meet the standard, the sample pretreatment and detection must be repeated.
[0077] This step establishes a mechanism for determining the validity of test results through dual verification of spiked recovery and parallel experiments, ensuring the accuracy, repeatability, and stability of the test method and guaranteeing the reliability of the final test data.
[0078] In some embodiments, the nitrobenzene compounds include one or more of nitrobenzene, o-nitrotoluene, m-nitrotoluene, p-nitrotoluene, and 2,4-dinitrotoluene.
[0079] Specifically, this detection method can simultaneously detect single components or multiple mixed nitrobenzene compounds. It sets specific chromatographic separation parameters and characteristic ion parameters for each compound, and can simultaneously complete the qualitative and quantitative detection of five nitrobenzene compounds. It has a wide range of applications and meets the high-throughput detection needs of multiple nitrobenzene compound residues in aquatic products.
[0080] This invention constructs a fully optimized detection system for nitrobenzene compounds in aquatic products. It utilizes homogenized ultrasonic-assisted extraction to improve the dissolution efficiency of target compounds, combined with drying and solid-phase extraction to thoroughly eliminate matrix interference, temperature-programmed separation with selected ion monitoring to achieve specific signal acquisition, dual-dimensional qualitative determination to avoid false positives, matrix-matched standard curves for accurate quantification, and dual experimental verification of results. The targeted optimization of all stages, from sample pretreatment to instrument detection and result verification, solves the technical problems of large matrix interference, low extraction efficiency, and inaccurate qualitative and quantitative analysis in traditional detection methods. This significantly improves the sensitivity, accuracy, stability, and applicability of the detection method, demonstrating outstanding substantial technological advancement and application value in food safety testing.
[0081] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the claimed invention. The scope of protection claimed by the appended claims and their equivalents is defined.
Claims
1. A method for detecting nitrobenzene compounds in aquatic products, characterized in that, include: The aquatic product samples to be tested were homogenized and crushed, and after adding the extraction solvent, ultrasonic-assisted extraction was performed, followed by centrifugation to obtain the primary extract. The primary extract was purified and concentrated by a combination of solid-phase extraction and anhydrous drying to remove interference from fat and protein matrices, and the sample solution to be tested was prepared. The sample solution was injected into a gas chromatograph-mass spectrometer, and the characteristic signals of nitrobenzene compounds were collected by temperature-programmed chromatography and selected ion monitoring mode. The retention time and characteristic ion abundance ratio of the sample are compared with the data of the standard to complete the qualitative determination of nitrobenzene compounds; The content of nitrobenzene compounds in the sample was calculated based on the peak area of characteristic ions using the matrix-matched standard curve method. The validity of the final test data is determined by verifying the test results through spiked recovery and parallel experiments.
2. The method for detecting nitrobenzene compounds in aquatic products according to claim 1, characterized in that, The aquatic product samples to be tested were homogenized and crushed, and after adding the extraction solvent, ultrasonic-assisted extraction was performed. The primary extract was obtained by centrifugation, including: Weigh the homogenized aquatic product sample, add dichloromethane-based extraction solvent, mix by high-speed vortexing, and then extract by constant-temperature ultrasonic extraction. The mixture is centrifuged at high speed, and the supernatant obtained is the primary extract.
3. The method for detecting nitrobenzene compounds in aquatic products according to claim 1, characterized in that, The primary extract was purified and concentrated using a combination of solid-phase extraction and anhydrous drying to remove interference from lipid and protein matrices, resulting in the sample solution for testing, which includes: Anhydrous desiccant was added to the primary extract to dehydrate it, and the solid desiccant was removed by filtration and then concentrated by nitrogen blowing. The concentrate was purified by an activated solid-phase extraction column, the target analyte was eluted and the volume was adjusted to obtain the sample solution to be tested.
4. The method for detecting nitrobenzene compounds in aquatic products according to claim 1, characterized in that, The sample solution was injected into a gas chromatograph-mass spectrometer, and characteristic signals of nitrobenzene compounds were acquired using temperature-programmed chromatography and selected ion monitoring mode, including: A capillary column was used, and chromatographic separation was completed by setting the injection port temperature and the programmed temperature gradient. An electron impact ion source was used, and the characteristic quantitative and qualitative ion peak areas of nitrobenzene compounds were collected using the selected ion monitoring mode.
5. The method for detecting nitrobenzene compounds in aquatic products according to claim 1, characterized in that, The retention time and characteristic ion abundance ratio of the sample are compared with the data of the standard to complete the qualitative determination of nitrobenzene compounds, including: Compare the consistency of chromatographic retention times between the sample and the standard; When the deviations in the abundance ratios of characteristic ions between the sample and the standard both meet the standard requirements, the corresponding nitrobenzene compound is determined to be detected.
6. The method for detecting nitrobenzene compounds in aquatic products according to claim 1, characterized in that, The content of nitrobenzene compounds in the sample was calculated based on the characteristic ion peak area using the matrix-matched standard curve method, including: Prepare a series of standard working solutions with concentrations matching the sample matrix, and plot a concentration-peak area standard curve; Substitute the characteristic ion peak area of the sample into the standard curve, and calculate the actual content of nitrobenzene compounds in aquatic products by combining the pretreatment dilution factor.
7. The method for detecting nitrobenzene compounds in aquatic products according to claim 1, characterized in that, The validity of the final test data is determined by verifying the test results through spiked recovery and parallel experiments, including: Perform spiked recovery tests on blank samples and calculate the method recovery rate; Perform multiple parallel tests on the same sample and calculate the method precision. The test results are considered valid when both the recovery rate and precision are within the preset acceptable range.
8. The method of claim 3, wherein the nitrobenzene compound is 4-nitrophenol. The concentrate was purified using an activated solid-phase extraction column, the target analyte was eluted, and the volume was adjusted, including: The solid-phase extraction column was activated and eluted sequentially with organic solvents; After the concentrated solution is loaded with the adsorption solution, the target analyte is eluted with an eluent, the eluent is collected and concentrated by nitrogen blowing, and then an organic solvent is added to make up to a fixed volume.
9. The method of claim 4, wherein the nitrobenzene compound is 4-nitrophenol. Using a capillary column, chromatographic separation is achieved by setting the injection port temperature and the programmed temperature gradient, including: An inert capillary column was used, and the injection port temperature and constant carrier gas flow rate were set. By setting the initial column temperature, heating rate, and termination column temperature, the complete separation of nitrobenzene compounds can be achieved.
10. The method for detecting nitrobenzene compounds in aquatic products according to claim 1, characterized in that, The nitrobenzene compounds include one or more of nitrobenzene, o-nitrotoluene, m-nitrotoluene, p-nitrotoluene, and 2,4-dinitrotoluene.