三唑磷在苹果中的残留检测方法及残留动态

Detection and degradation of triazophos in apple

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0．05ng，最低检出浓度（LDQ）为0．02mg／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：（D三唑磷在苹果中的半衰期20．6—22．8d，在土壤中的半衰期为10．7～15．4d。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。（D用20％三唑磷乳油2000倍液施药2次，距末次施药后30d采样测定，全果中的残留量为0．061～0．139mg／kg，低于WHO／FAO规定的三唑磷在梨果类水果中的MRL值0．2mg,／kg。

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 ap- ple 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）.