The Establishment And Application Of Rapid Screening System In Analysis On Determination Of Pesticide Residues

Pesticides have a wide range of applications as an important means of plant protection. The widespread use of these compounds has increased the public concern on the presence of their residues in tea, a agricultural product, which represents the culture characteristics of China. So it is of significant importance to evaluate the safety of Chinese tea products.Two comprehensive screening mass spectrometry libraries of 247 pesticides were developed using UPLC-Q-Orbitrap-MS and HPLC-MS.Mean while, considering the complex features of tea matrix, a confirmation method for the detection of 145 pesticides with modified QuEChERS sample preparation coupled with triple quadrupole tandem mass spectrometry (TQ 8050) and quadrupole-oribitrap mass spectrometry (Q-Exactive) were established, respectively. The linearity of the external standard calibration curves was satisfied and the coefficients of determination (r) were not less than 0.99. The limits of detection (LODs) for TQ 850 were 0.03-3.1μg/kg, and for Q-Exactive were 0.03～3.7μg/kg in blank tea sample. The recoveries by bland spiked samples at low, medium, and high fortification levels ranged from 62.2%～118.8% (TQ 8050) and 59.1%～117.4% (Q-Exactive), with the relative standard deviation (RSD) below 23.8%. The method validation results demonstrate that the established method is sensitive and specific enough for the analysis of pesticides residues in tea samples.Residue analysis and pollution level investigation of 191 tea samples including samples of tea bags and teas were developed with the established screening system and detection methods. By the statistical test, there is no obvious difference in the safety of the raw materials of tea bags and other teas. There were 41 pesticides were detected in the collected tea samples, including imidacloprid, buprofezin, triazophos, acetimipirid, carbendazim and chlorpyrifos, etc.. The pesticide residuea status in tea samples in tea is consistent with the pesticide registration status on teas. And the major residues were with the detection ratio and concentration of 50.8% (not detected (ND)～2.084 mg/kg),45.5%(ND～1.229 mg/kg),34.0%(ND～0.465 mg/kg), 31.9%(ND-1.895 mg/kg),29.8%(ND～1.208 mg/kg),29.8%(ND～1.163 mg/kg). Overall, the majority pesticides residues in tea are accordance with the national standard limited requirements. However, there are still some tea samples with the residue levels violating the limits of the National Food Safety Standards according to GB 2763 (Maximum residue limits for pesticides in food), thus strengthening the implementation of good agricultural practice, strengthen the supervision and management and monitoring is indispensable.