Xây dựng quy trình phân tích đồng thời dư lượng một số thuốc trừ sâu nhóm phospho hữu cơ sử dụng phổ biến trong rau ăn lá, quả bằng phương pháp LC- MS/MS

A reversed-phase LC-MS/MS method was successfully developed for simultaneous determination of clopyrifos (CLO), diazinon (DIA), dimethoate (DIM), fenitrothion (FEN) in real vegetable samples with the following optimized conditions: column Agilent Eclipse Plus C18 (4,6 x 150 mm; 3,5 µm); the gradient mode of mobile phases including H₂O: MeOH; the flow rate 0.9 ml/min; sample injection volume 10 μl; Electrospray ionization source was operated in positive mode and multi reaction monitoring (MRM) mode using the transition of m/z 351.82 “ 96.77,  m/z 305.01 “ 168.97, m/z 299.91 “ 198.84, and m/z 278.23 “ 124.85  were used to quantify CLO, DIA, DIM and FEN, respectively. This method was validated basing on EC-657/2002 guideline to meet all the requirements of wide linearity range of 3 – 125 ppb, high correlation coefficients  (R² > 0.9958), very good accuracy (recovery rate 98.7 – 104.5%) and intermediate precision (RSD < 7 %), typical LOD, LOQ values of 0.0001 – 1 ppb and 0.005 – 2 ppb for four oranophosphate pesticides. The validated method was used in a 30 real samples survey. The results indicated that nine vegetable samples (30%) contain target pesticide residues below Vietnam Ministry of Health s MRLs.

Key words: Diazinon, dimethoate, clopyrifos, fenitrothion, QuEChERS, inter-day precision.

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