气相色谱-质谱法测定乙螨唑在苹果和土壤中的残留及消解动态

Residues and decline study of etoxazole in apple and soil by gas chromatography-mass spectrometry method

采用气相色谱-质谱联用（GC-MS）法,测定了乙螨唑在苹果和土壤中的残留及消解动态。土壤样品经丙酮提取,苹果样品经V（丙酮）∶V（乙酸乙酯）=1∶1混合溶液提取,两者均无需净化,采用气相色谱-质谱联用（GC-MS）仪测定。结果表明：在0.01、0.1和1 mg/kg 3个添加水平下,乙螨唑在苹果中的平均回收率为93%-96%,相对标准偏差（RSD）为2.8%-8.0%;在土壤中的平均回收率为91%-104%,RSD为0.70%-8.3%;最小检出量为0.001 ng,最低检测浓度为0.01 mg/kg。国际食品法典委员会（CAC）、中国和美国均未制定乙螨唑在苹果上的最大残留限量值（MRL）,日本规定乙螨唑在苹果上的MRL值为2.0 mg/kg。本研究参考日本规定,采用150 g/L乙螨唑悬浮剂按有效成分30 mg/L剂量（推荐剂量的1.5倍）施药,其在苹果和土壤中的半衰期分别为7.4-14.2 d和4.2-18.1 d,施药后21 d苹果中乙螨唑的最终残留量≤1.65 mg/kg。

A gas chromatography-mass spectrometry（ GS-MS） method was developed for determining etoxazole residues in apple and soil. The soil samples were extracted with acetone and the apple samples were estracted with a mixture of proportionate acetone and ethyl acetate（ 1 ∶ 1,V / V）. All the samples were tested by GC-MS without cleanup. Results showed that the ranges of average recoveries and relative standard deviations of the method were 93% to 96% in apple and 91% to 104% in soil,2. 8% to 8. 0% in apple and 0. 70% to 8. 3% in soil respectively,at fortified levels of 0. 01 to1 mg / kg. The limit of detection was estimated to be 0. 001 ng,and the limit of quantification was0. 01 mg / kg. International codex alimentarius commission（ CAC）,China and the United States do not stipulate the MRL of etoxazole in apple but the MRL is 2. 0 mg / kg in Japan. Refer to the stipulation,sprayed with high dosage of 30 mg（ a. i.） / L for etoxazole 150 g / L EW,the results of residue dynamics indicated that the half-lives of etoxazole in apple and soil were 7. 4- 14. 2 d and 4. 2-18. 1 d,respectively. Terminal residues in apples were less 1. 65 mg / kg after 21 days.