Determination of Residual Mancozeb in Peanuts Sample by MethylationDerivation-High Performance Liquid Chromatography

A simple and rapid method was developed for the residue determination of mancozeb. Mancozeb in peanuts sample was extracted by the mixed solution of L-cysteine and EDTA-2Na. After that,0.05 mol/L methyl iodide in trichloromethane-hexane(3∶ 1 ,V/V) was added into the extracts. Then the organic layer was took out and concentrated and dissolved in acetonitrile for HPLC by λ272 nm. In the method,mancozeb was analyzed on a Agilent TC-C18 column,using a mixture of acetonitrile-water (50∶ 50,V/V) as the mobile phase at the ambient temperature with a flow rate of 1.0 mL/min. The average recoveries of mancozeb in peanuts at 0.05,0.5 and 2.0 mg/kg fortification level were 76.1% ~86.2%,and the coefficient of variation were 0.7% ~10.2%. The limit of detection (LOD) was 0.02 mg/kg,and the limit of quantitation (LOQ) was 0.05 mg/kg.