Residue analysis method of thiadiazole derived pesticides in kiwi fruit

Aiming to optimize the residue analysis methods of thiadiazole derived pesticides in kiwi fruits, a method based on the modified QuEChERS method coupled with UPLC-MS/MS was developed. The target pesticides were transformed into thiadiazole by reacting with NaOH and adjusting the pH to 2 ~ 3 with HCl. Then thiadiazole was extracted with acetonitrile, salted out with NaCl, cleaned up with C₁₈ and GCB, and detected with UPLC-MS/MS. The results showed that the correlation coefficient (r) was no less than 0.999 within the concentration range from 0.001 to 0.5 mg/L, which indicated a satisfactory linear relation between the areas and the concentrations of thiazole zinc(THIA), thiediazole copper(THIE), thiosen copper(THIO) and thiediazole(AMT). Meanwhile, the average recoveries of THIA, THIE, THIO and AMT were 81% ~ 93% with the maxium RSD of 9.3% at the spiked concentration of 0.01 to 1 mg/kg which indicated that the accuracy and precision of the method met the requirements of residue analysis. The limit of quantification (LOQ) was 0.01 mg/kg, showing the high sensitivity of the method. Compared with the exiting traditional methods, this new developed method has greater universality, higher sensitivity and more efficiency, and the sample preparation process is safer and environmental friendly, which is helpful to improve the residue risk monitoring levels of thiadiazole derived pesticides.