苹果和土壤中丙森锌的消解动态及残留规律

研究了苹果和土壤中丙森锌残留的气相色谱分析方法,及其代谢物乙撑硫脲的高效液相色谱分析方法,并在天津、山东烟台和陕西咸阳进行了苹果和土壤中丙森锌及其代谢物乙撑硫脲残留消解动态和残留规律田间试验研究.结果表明,在0.05—2 mg.kg-1的加标水平下,苹果和土壤中丙森锌的加标回收率分别为77.12%—92.85%和9.24%—94.68%,变异系数分别为3.30%—6.56%和3.29%—5.29%;在0.05—1 mg.kg-1的加标水平下,苹果和土壤中乙撑硫脲的加标回收率分别为80.91%—97.47%和84.11%—99.97%,变异系数分别为3.23%—3.82%和2.80%—3.40%.苹果和土壤中丙森锌和乙撑硫脲的最小检出量分别为5.0×10-10g和1.0×10-10g,其中苹果和土壤中丙森锌的最低检出浓度为0.025 mg.kg-1,乙撑硫脲的最低检出浓度为0.005 mg.kg-1.按1.5倍推荐剂量600倍稀释液在苹果上施用65%戊唑醇.丙森锌可湿性粉剂1次,丙森锌在苹果和土壤中的残留消解半衰期分别为6.0—6.8 d和8.7—10.1 d.按推荐剂量和1.5倍推荐剂量在苹果上各施用65%戊唑醇.丙森锌可湿性粉剂3—4次,2次施药间隔为10 d,距最后一次施药21 d时,丙森锌在苹果中的最高残留量低于我国农业行业标准规定的最大残留限量2 mg.kg-1.

Residue dissipation dynamics of propineb in apples and soils

An analytical method using gas chromatography to determine the residue of propineb in apple and soil was developed.The metabolite propylenethiourea was detected by HPLC method.The results showed that recoveries from untreated samples with added propineb at 0.05,0.50,2.00 mg · kg-1 were 77.12%—92.85% and 9.24%—94.68%,with the variation coefficients of 3.30%—6.56% and 3.29%—5.29% in apples and soils,respectively.The recovery rates and the relative standard deviations of propylenethiourea were 80.91%—97.47% and 3.23%—3.82% in apples,and 84.11%—99.97% and 2.80%—3.40% in soils,respectively,at the spiking levels of 0.05,0.50,1.00 mg · kg-1.The detectable concentration was 0.025 mg · kg-1 for propineb and 0.005 mg · kg-1 for propylenethiourea in apples and soils.The residue and dissipation dynamics of propineb propylenethiourea in apple and soil under field experiments in Tianjin,Shandong and Shanxi were investigated.It was found that the dissipation half-life of propineb in apples and soils was 6.0—6.8 d and 8.7—10.1 d,respectively.When the recommended dosage and 1.5 times recommended dosages of 65% Tebuconazole Propineb wettable powder was sprayed for 3—4 times at an interval of 10 d,the maximum residual concentration of propineb on the 21st day after the last application was lower than the MRL of propineb in the apples according to standards of Ministry of Agriculture of China(2 mg · kg-1).