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.