Application Of Comprehensive Two-dimensional Gas Chromatography Coupled With Time-of-flight Mass Spectrometry For Detecting Organophosphorus And Organochlorine Pesticide Residues

Gas chromatography tandem mass spectrometry combines the separation performance of gas chromatography with the qualitative and quantitative characteristics of mass spectrometry,and plays an important role in modern analysis.However,with the increasing complexity and variety of analytical components,conventional one-dimensional gas chromatography tandem mass spectrometry cannot provide sufficient separation of complex mixtures.Impurities and target analytes are often co-eluted,resulting in poor analytical results.Comprehensive two-dimensional gas chromatography coupled with time-of-flight mass spectrometry technology combines the excellent separation ability and peak capacity of comprehensive two-dimensional gas chromatography with the high acquisition frequency,high sensitivity,high selectivity and other advantages of time-of-flight mass spectrometry.It has qualitative and quantitative capabilities,effectively solves the problems of co-elution of components and shortage of peak capacity in conventional one-dimensional gas chromatography.It plays an important role in modern analysis fields such as petrochemical,biomedical,food safety,and environmental testing.However,the application and systematic evaluation of this technology in the field of pesticide residue analysis are obviously insufficient.In this paper,for the first time,typical pesticide varieties were studied systematically in different sample matrixes,and the characteristics of the application of comprehensive two-dimensional gas chromatography coupled with time-of-flight mass spectrometry in pesticide residues analysis were evaluated,77 organophosphorus and 23 organochlorine pesticide residue methods were established,the main results were as follows:1.Optimized the key parameters such as ion source temperature,carrier gas flow rate,modulation period,modulator compensation temperature,thermal blowing time of the comprehensive two-dimensional gas chromatography coupled with time-of-flight mass spectrometer for 77 organophosphorus and 23 organochlorine pesticides.The differences and advantages in chromatographic separation between comprehensive two-dimensional gas chromatography coupled with time-of-flight mass spectrometry and conventional one-dimensional gas chromatography tandem mass spectrometry were compared,comprehensive two-dimensional gas chromatography coupled with time-of-flight mass spectrometry could better solve the co-elution problem of 25 pesticides such as Pentachloronitrobenzene,Dioxathion and beta-BHC.Compared with previous studies,the method established in this study could separate 100 target pesticides in a shorter analysis time(37 minutes),and the resolution of target analytes was improved.2.A method for the residual analysis of organophosphorus and organochlorine pesticides in plant-derived food matrixes on comprehensive two-dimensional gas chromatography coupled with time-of-flight mass spectrometry was established.The recoveries of target pesticides in plant-derived food matrixes ranged from 72.6%～117.5%,and the relative standard deviation(RSD)ranged from0.1%～19.9%,the limit of quantitation(LOQ)of all target pesticides in the apples,tomatoes,oranges,potatoes and dried broad beans matrixes was 10 μg/kg,and in the peanut matrix,the LOQ of acephate,omethoate,monocrotophos,paraoxon-methyl,fenthion sulfoxide and coumaphos was 50 μg/kg,while the LOQ of the remaining target pesticides was 10 μg/kg.It had good linearity,accuracy,sensitivity and stability,and met the requirements of the residue analysis method.The matrix effect of the plant-derived food was also discussed and it was found that the unsaturated fatty acids,vitamins and other groups in the substrate of plant-derived food produced interference on the target pesticides,and effective measures were needed to remove these interfering components to reduce the matrix effect in order to obtain accurate results.3.Organophosphorus and organochlorine pesticides in soil and water of environmental matrixes were determined by comprehensive two-dimensional gas chromatography coupled with time-of-flight mass spectrometry.The recoveries of target pesticides in environmental matrixes ranged from72.3%～118.3%,and the relative standard deviations ranged from 0.1%～29.9%.The LOQ of target pesticides was 10 μg/kg in soil matrix and 0.1 μg/kg in water matrix.The method met the requirement of pesticide residue analysis.The matrix effect of the environmental matrixes was discussed.Interfering chromatographic peaks were produced by organic substances or minerals in the soil matrix,and interferences need to be removed to obtain more reliable results.4.Based on the results of the study,the application performance of comprehensive two-dimensional gas chromatography coupled with time-of-flight mass spectrometry was evaluated as follows: comprehensive two-dimensional gas chromatography coupled with time-of-flight mass spectrometry can be used to analyze organophosphorus and organochlorine pesticides in plant-derived food matrixes and environmental matrixes in a relatively short time,is an effective technique for the separation of complex components in the field of analysis,and its excellent separation,qualitative and quantitative characteristics are expected to have a good application prospect in the field of pesticide residue analysis.