Study On The Residue Dynamics Of Mancozeb And Etylenethiourea In Apple And Soil

A rapid method has been developed for the determination of germicide mancozeb and ETU residues in apple and in soil. The residual behavior of mancozeb in apple and soil were studied in field. And the suggestion of reasonable utilization were proposed.In this study a rapid method has been developed for the determination of germicide mancozeb residues in apple and soil.The mancozeb of the sample, which was methylated by dimethyl sulfate, was extracted by QuEChERS and detected by ultraperformance liquid chromatography-mass spectrometry under multiple reaction monitoring mode, then quantified by matrix-match standard solution. The qualitative results were obtained based on retention time, the precursor ion and two daughter ions, and the quantitation results were on the intension of the characteristic 241>117 ion and 241>193 ion. Average recoveries of mancozeb in apple samples were found in the range of 88.7～109.4% at threefour spiking levels from 0.005 mg/kg to 0.5 mg/kg with relative standard deviations of 5.9～8.7%. Limit of detections of mancozeb in apple were 2.5×10-4 mg/kg, while limit of quantifications were 8.3×10-4 mg/kg. Average recoveries of mancozeb in soil samples were found in the range of 70.9%～95.6% at spiking levels from 0.005 mg/kg to 0.5 mg/kg with relative standard deviations of 3.1%～5.9%. Limit of detections of mancozeb in soil were 3.9×10-4 mg/kg, while limit of quantifications were 1.2×10-3 mg/kg,respectively.In this study a rapid method has been developed for the determination of germicide ETU residues in apple and soil. The ETU of apple sample was extracted by the methanol.The extraction were cleaned up by C18 SPE.The ETU of soil sample was extracted by the mixture solution of methanol:water=3:1. The extraction were cleaned up by PSA.And the ETU wasdetected by ultraperformance liquid chromatography-mass spectrometry under multiple reaction monitoring mode, then quantified by standard solution. Average recoveries of ETU in soil samples were found in the range of为89.9～91.2% at spiking levels from 0.005 mg/kg to 0.5 mg/kg with relative standard deviations of 2.5-3.6%. Limit of detections of ETU in apple were 1.3×10-3 mg/kg, while limit of quantifications were 4.3×10-3 mg/kg. Average recoveries of ETU in apple samples were found in the range of 87.6～89.7% at spiking levels from 0.005 mg/kg to 0.5 mg/kg, with relative standard deviations of 6.6～12.4. Limit of detections of ETU in soil were 1.2×10-3 mg/kg, while limit of quantifications were 4.1×10-3 mg/kg, respectively.The field trials of mancozeb in apple were conducted in three experimental fields located in Beijing,Shangdong and Henan provinces respectively. It was demonstrated from the results that the degradation dynamics of mancozeb in apple and soil accorded with the kinetic equation,and the relativity was good. The half life of mancozeb in soil were 0.19～8.3 d, and that in apple were3.0～14.8 d respectively.