Studies And Application Of High-throughput Detection Technologies Of Pesticide Residues In Foods Of Plant Origin

Pesticides can effectively control plant diseases, pests and weeds in agricultural production, and have very important roles in improving the output and quality of agricultural products. But negative effects become more and more serious due to non-standard use of pesticides, the residues of pesticides in edible agricultural products,in particular,have brought about great risk to the health of consumers. In recent years, in order to ensure the safety of food consumption, the monitoring of pesticide residues in edible agricultural products were steped up in many countries, more test items and lower determination limits brought serious challenge to determination works of pesticide residues in China. This topic focused on the sample pretreatment of Qu ECh ERS and composite molecular imprinting solid phase extraction combined with determination by high performance liquid chromatography-mass spectrometry, the studies on high-throughput determination of pesticide residues in fruits, vegetables and cereal grains was carried out. The main contents and results are as follows:A method for the simultaneous determination of 21 carbamate residues in fruits and vegetables by liquid chromatography-tandem mass spectrometry(LC-MS/MS) was developed. The samples were extracted with acetonitrile containing 1% acetic acid, and each 3 m L extraction solution was cleaned-up by dispersive-solid phase extraction(D-SPE)after 900 mg Mg SO4, 150 mg ethylenediamine-N-propyl silyl( PSA) and 40 mg graphitized carbon black( GCB) were added. The target analytes were quantified by LC-MS/MS in a positive ion multiple reaction mode(MRM). The results showed that linear ranges of concentrations of 21 carbamate pesticides were 0.5-20 ng/m L, the correlation coefficients were all above 0.99. The recoveries of the 21 target analytes in Chinese flowering cabbage, cucumber, grape and banana ranged from 71.6% to 119.8% with the relative standard deviations(RSDs) from 2.4% to 23.0% at spiked levels of 10, 20 and 50 μg/kg. The method was demonstrated to be simple, sensitive and reliable, and can meet the requirements for the routine determination of a variety of carbamate pesticide residues in fruits and vegetables.A method was developed for the simultaneous determination of 127 pesticide residues in fruits and vegetables by liquid chromatography-tandem mass spectrometry(LC-MS/MS) combined with optimized Qu ECh ERS method. The sample was prepared by the modified Qu ECh ERS method, extracted with acetonitrile containing 1% acetic acid, and cleaned-up by adding gethylenediamine-N-propyl silyl(PSA) and graphitized carbon black(GCB). The extract was detected by liquid chromatography-tandem mass spectrometry(LC-MS/MS) under multiple reaction monitoring(MRM) mode and quantified by the external standard method. The calibration curves of 127 pesticide residues were linear in the range of 0.5ng/m L-40 ng/m L with correlation coefficients more than 0.99.The recoveries for all compounds in Chinese flowering cabbage, cucumber, grape and banana were at the range of 60.5%-118.5% with the relative standard deviations(RSDs) from 2.4% to 23.0% at spiked levels. The limits of quantitation(LOQs,S /N≥10) for 127 pesticides were less than 8.9μg/kg. The method was demonstrated to be simple, rapid, sensitive and reliable, and successfully used for the screening and determination of many kinds of pesticide residues in fruits and vegetables.A new multi-residue analytical method was developed for the simultaneous determination of 20 triazine and sulfonylurea herbicides residues in foods of plant origin by high performance liquid chromatography-tandem mass spectrometry(HPLC-MS/MS) combined with composite molecular imprinting solid phase extract(C-MIP-SPE). The samples was extracted with acetonitrile and then cleaned with liquid-liquid extraction and composite molecular imprinting solid phase extraction. The target compounds were separated with Agilent ZORBAX RX-C8 column(150 mm×2.1 mm, 5μm). The mobile phase A(acetonitrile) and the mobile phase B(1% formic acid solution) were used in a gradient elution program. The target herbicides were detected by electrospray ionization mass spectrometry in positive ion mode with multi reaction monitoring(MRM). The result showed good linear relationships in the range of 0.5ng/m L-20ng/m L and the correlation coefficients were all above 0.99. The recoveries at spiked levels of 5μg/kg, 10μg/kg, 20 μg/kg for 20 target compounds in com samples were at the range of 62.7%-117.4%, with relative standard deviations of 1.7%~13.9%. The limits of quantitation(LOQs,S /N≥10) for 20 pesticides were less than 2.1 μg/kg. The method was demonstrated to be specific, sensitive and accurate, and could be used for the determination of 20 triazine and sulfonylurea herbicides residues in foods of plant origin.In conclusion, analytical methods of multiple pesticide residues in fruits, vegetables and cereal grains were studied in this paper. The methods were established on the basis of the newest test items and technologies, and conform the current trend of the determination of pesticide residues. The pretreatment processes, the conditions of chromatographic and mass spectrometry were discussed and the methodological indicators were investigated in the study. The methods were applied to determination of the real samples, have a good practical value.