Residue analysis of flucarbazone-sodium, mesosulfuron-methyl, clodinafop-propargyl and clodinafop in wheat

A modified QuEChERS method was developed and validated for the determination of flucarbazone-sodium, mesosulfuron-methyl, clodinafop-propargyl and clodinafop in wheat kernel and straw by high-performance liquid chromatography coupled with tandem mass spectrometry (HPLC-MS/MS). The wheat kernel was extracted with 10 mL acetonitrile, after 5 mL 0.1% formic acid solution was added to improve the extraction efficiency. Samples were cleaned up by 50 mg C₁₈ and 100 mg anhydrous MgSO₄. After adding 10 mL 2% formic acid solution, the wheat straw was extracted with 10 mL acetonitrile. 100 mg C₁₈ and 200 mg anhydrous MgSO₄ were used to clean up the samples. The average recoveries of four compounds in wheat kernel and wheat straw were 76%-97% and 83%-102%, respectively, with the relative standard deviations (RSDs) for those four compounds less than 10%. Good linearity was achieved with determination coefficients higher than 0.99. The limit of quantity (LOQ) is 0.005 mg/kg for flucarbazone-sodium, 0.01 mg/kg for mesosulfuron-methyl, 0.05 mg/kg for clodinafop-propargyl and clodinafop. This method meets the requirements of pesticide residue analysis.