烯啶虫胺在水稻和稻田环境中的残留及消解动态

采用高效液相色谱-紫外检测器(HPLC-UVD)测定了烯啶虫胺在稻田水、土壤、水稻植株和糙米样品中的消解动态及最终残留。田水样品用二氯甲烷萃取;土壤样品用水提取后经二氯甲烷萃取;水稻植株和糙米样品依次用水、丙酮提取,提取液经液液萃取及柱层析净化;HPLC-UVD检测。当烯啶虫胺在田水和土壤中的添加水平为0.1~5 mg/L和0.1~5 mg/kg,在植株和糙米中的添加水平为0.2~5 mg/kg时,其平均添加回收率在77.2% ~100.3%之间,相对标准偏差 (RSD)在1.9% ~12.9%之间。烯啶虫胺在稻田水、土壤、植株和糙米中方法的定量限(LOQ)分别为0.1 mg/L和0.1、0.2、0.2 mg/kg,检出限(LOD)分别为0.04 mg/L和0.04、0.08、0.08 mg/kg。温室模拟消解动态试验结果显示,以推荐使用高剂量的20倍(有效成分1 500 g/hm2) 施药,烯啶虫胺在稻田水、土壤以及水稻植株中的消解动态规律均符合一级动力学方程,其半衰期分别为0.58、3.31及2.70 d,消解速率较快。最终残留试验表明,于大田分蘖期按推荐使用高剂量的1.5倍(有效成分112.5 g/hm2)分别施药3次和4次,间隔期为7 d,距最后一次施药7 d后采样,糙米中烯啶虫胺的残留量均低于LOD值(0.08 mg/kg)及日本规定的最大残留限量(MRL)值(0.5 mg/kg)。

Residue and decline dynamics of nitenpyram in rice and rice field

The residual dynamics and final residues of nitenpyram in water,soil,paddy and rice samples in supervised field residue trials were determined by high performance liquid chromatography equipped with ultraviolet detector (HPLC-UVD).Water samples were extracted with methylene chloride.Soil samples were extracted with water only,and paddy and rice samples firstly with water then with acetone.The extracts were cleaned up by liquid-liquid extraction,and further cleaned up by column chromatography.Under the fortified level 0.1 to 5 mg/L for water,0.1 to 5 mg/kg for soil,and 0.2 to 5 mg/kg for paddy and rice,the recovery ranged from 77.2% to 100.3% with the relative standard deviations of 1.9%-12.9%.The limit of quantification (LOQ) of the method was 0.1 mg/L for water,0.1 mg/kg for soil,0.2 mg/kg for paddy and rice.The limit of detection (LOD) of the method was 0.04 mg/L for water,0.04 mg/kg for soil,0.08 mg/kg for paddy and rice.The results of simulating dynamic test in greenhouse showed that applied at exaggerated rate of dosage (1 500 g a.i./hm²), the half-life of nitenpyram was 0.58 days in water,3.31 days in soil and 2.70 days in paddy,respectively.When sprayed for 3 and 4 times at 1.5 times of the recommended dosage (112.5 g a.i./hm²),at interval time of 7 d after the last application,the final residues of nitenpyram in rice were lower than LOD (0.08 mg/kg) or the MRL of Japan (0.5 mg/kg).