乙螨唑在9种水果蔬菜样品基质中的残留储藏稳定性

建立了乙螨唑在不同样本基质（猕猴桃、木瓜、柠檬、茄子、山楂、柿子、甜椒、香蕉以及枣）中的气相色谱-质谱 (GC-MS) 分析方法，进而系统研究了?20 ℃条件下乙螨唑在上述果蔬中储藏112 d的稳定性差异及其影响因素。样品经乙腈提取，氨丙基固相萃取柱净化，GC-MS检测分析。结果表明:在0.01~3 mg/kg添加水平下，乙螨唑在9种果蔬中的平均回收率在80%~112%之间，相对标准偏差在1.4%~12%之间，定量限为0.01 mg/kg。于 ?20 ℃下储藏14~112 d期间，乙螨唑在甜椒中的降解率为9.0%~28.6% (低于30%)，说明其具有较好的储藏稳定性；但在猕猴桃、木瓜、柠檬、茄子、山楂、柿子、香蕉和枣中，其降解率均超过30%，储藏稳定性较差。乙螨唑残留储藏稳定性与样本基质的种类、pH值、含水量等密切相关。因此，乙螨唑的残留试验样本不宜长时间储藏，获取后应当尽快检测，以防农药降解导致检测结果出现偏差。本研究为乙螨唑在多种果蔬作物中的残留检测方法和储藏稳定性提供了基础数据，也为后续乙螨唑的准确定量分析提供了理论参考。

Residual storage stability of etoxazole in 9 kinds of fruits and vegetables

A gas chromatography-mass spectrometry (GC-MS) method was developed for etoxazole in kiwifruit, papaya, lemon, eggplant, hawthorn, persimmon, sweet pepper, banana and jujube. Then, the storage stabilities and influencing factors of etoxazole were evaluated systematically in above crops at ?20 ℃ for 112 days. The samples were extracted by acetonitrile, purified by aminopropyl solid phase extraction cartridge, and determined by GC-MS. The results showed that the mean recoveries were between 80% and 112%, the relative standard deviations (RSD) were ranged from 1.4% to 12% at the spiking level of 0.01-3 mg/kg, and the limit of quantification was 0.01 mg/kg. Etoxazole was relatively stable in sweet pepper with degradation rates of 9.0%-28.6%, which were lower than 30%. However, the degradation rates of etoxazole were over 30% in kiwifruit, papaya, lemon, eggplant, hawthorn, persimmon, banana and jujube, demonstrating etoxazole could not be stored stably. The storage stability of etoxazole was closely related to the types of matrix, pH values and water content. Therefore, the samples with etoxazole residues are not recommended to be stored for a long time and should be detected as soon as possible to avoid the deviation of detection results caused by pesticide degradation. This study provided basic data for residue analytical method and storage stability of etoxazole in a variety of fruit and vegetable crops, and also provides reference for accurate quantitation of etoxazole in further studies.