三唑磷在苹果中的残留检测方法及残留动态

采用气相色谱法建立了苹果和土壤中三唑磷残留量检测方法。样品中残留的三唑磷用乙酸乙酯提取,硅胶柱净化,气相色谱氮磷检测器测定。检测方法研究发现,三唑磷在苹果中存在基质响应增强效应,采用含有苹果基质的标准溶液进行校正可以消除基质效应的干扰。方法最小检出量(LOD)为0.05 ng,最低检出浓度(LDQ)为0.02 mg/kg,3个添加水平的平均回收率为89.1%~95.0%,相对标准偏差(RSD)为3.4%~8.6%(n=5)。残留研究表明:①三唑磷在苹果中的半衰期20.6~22.8 d,在土壤中的半衰期为10.7~15.4 d。②三唑磷在苹果中的残留量随着施药浓度和施药次数的增加而增加,随着采样间隔时间的延长而降低。③用20%三唑磷乳油2000倍液施药2次,距末次施药后30 d采样测定,全果中的残留量为0.061~0.139 mg/kg,低于WHO/FAO规定的三唑磷在梨果类水果中的MRL值0.2 mg/kg。

Detection and degradation of triazophos in apple

A method for determination of triazophos in apple and soil was developed.Residues were extracted from samples of apple and soil with ethyl acetate,followed by clean-up using silica gel column and determination using gas chromatography with nitrogen-phosphorus detection.The method explore discovered that triazophos displayed matrix-induced effects in apple sample.This effect was eliminated by using apple matrix-matched standard calibration.The limit of detection(LOD) of triazophos was 0.05 ng,and the limit of quantification(LOQ) of method for this pesticide was 0.02 mg/kg.Recoveries between 89.1 % and 95.0 % at three fortified level.The RSD ranged from 3.4 % to 8.6 %(n=5).The study of residues dynamic demonstrated that:(i) The half life of triazophos was 20.6-22.8 day in apple and 10.7-15.4 day in soil.(ii) The residues of triazophos was increased with the concentrate and frequency of applying the pesticide and decreased with time.(iii) 20 % triazophos was sprayed two times at a dose of 2000 times.After an interval of 30 day,the final residue in the apple was 0.061-0.0139 mg/kg,which was less than the maximum residue limit(MRL) of triazophos in pome fruit stipulated by WHO/FAO(0.2 mg/ kg).