Residue Decline Dynamics of Etoxazole in Orange and Soil by UPLC-MS/MS

A rapid,accurate and sensitive method has been developed to determine etoxazole residues in orange and soil by UPLC-MS/MS.The decline dynamics of etoxazole residues in orange and soil were studied under the conditon of field experiment.The samples were extracted by acetonitrile,followed by clean-up on silica gel cartridge and analyzed by UPLC-MS/MS.External reference method was used for quantitative determination.The linearity was satisfied (r=0.998 9) in the concentration range of 0.002-1 mg/L.The limit of detection was 6.0×10-6 μg,and the limit of quantification in orange and soil was 0.002 mg /kg.The average fortified recoveries varied from 87.3% to 98.4% with the coefficient of variation of 5.5%- 8.6%.The study of residue dynamics indicated that the curve of decline accorded with the first-order kinetics equation,and the half-life of etoxazole in orange and soil were 5.6- 7.6 d and 5.3- 8.6 d,respectively.