氯溴异氰尿酸在烟叶及其土壤中的残留分析及消解动态

Residues and decline dynamics of chloroisobromine cyanuric acid in tobacco and soil

建立了烟叶及其土壤中氯溴异氰尿酸残留的检测方法,并测定了氯溴异氰尿酸在烟叶及其土壤中的消解动态和最终残留。样品经乙腈提取,三氯甲烷、石油醚萃取后,采用高效液相色谱(HPLC-UV)检测。结果表明:在0.01～0.5 mg/kg添加水平下,氯溴异氰尿酸在鲜烟叶、干烟叶和土壤中的平均回收率分别为82.7%～91.6%、89.2%～91.8%和89.2%～94.4%,相对标准偏差(RSD)分别为1.1%～3.9%、2.6%～5.5%和1.5%～4.6%,方法的检出限(LOD)均为0.003 mg/kg,定量限(LOQ)均为0.01 mg/kg。田间消解动态结果表明,氯溴异氰尿酸在烟叶及其土壤中消解较快,半衰期分别为3.94～4.25 d和2.83～3.41 d,施药后14 d,其在烟叶和土壤中的消解率均达90%以上。氯溴异氰尿酸可湿性粉剂按有效成分600 g/hm2(推荐高剂量)和900 g/hm2(1.5倍推荐高剂量)于烟草现蕾期对水喷雾施药3～4次,距末次施药后间隔21 d采样,烟叶中氯溴异氰尿酸的残留量为1.47～3.52 mg/kg,土壤中的残留量为未检出～0.43 mg/kg。

The analytical method of fungicide chloroisobromine cyanuric acid and its residues and decline dynamics in tobacco and soil were investigated.Tobacco-leaf or soil samples were extracted with acetonitrile.The extracts were partitioned with trichloromethane and petroleum ether followed by determination with high performance liquid chromatography（HPLC） equipped with an ultraviolet（UV） detector.The average recovery at spiked levels of 0.01-0.5 mg/kg ranged from 82.7%-91.6% for fresh tobacco leaf,89.2%-91.8% for dried tobacco leaf and 89.2%-94.4% for soil,with relative standard deviations（RSD） of 1.1%-3.9%,2.6%-5.5% and 1.5%-4.6%,respectively.The limit of detection（LOD） and limit of quantification（LOQ） were determined as 0.003 and 0.01 mg/kg,respectively,for both tobacco and soil samples.Results of the decline dynamics study showed that half-life values（T1/2） were 3.94-4.25 d in fresh tobacco leaves and 2.83-3.41 d in soil,respectively.The ultimate residues of chloroisobromine cyanuric acid in dried tobacco leaves and soil were determined after the third and fourth application at levels of 600 g a.i./hm2 and 900 g a.i./hm2,with the residues ranging from 1.47-3.52 mg/kg in tobacco and below 0.43 mg/kg in soil 21 days after the last treatment.