Residue decline study of nitenpyram in orange and soil

A rapid,accurate and sensitive method has been developed to determine nitenpyram residues in orange and soil samples by UPLC-MS/MS.The degradation dynamics of nitenpyram residues in orange and soil were studied under condition of field trials.The samples were extracted by acetonitrile or methanol,and detected by UPLC-MS/MS.External reference method was used for quantitative determination.The linearity was satisfied (r>0.99) in the concentration range of 0.1-5 mg/L.The limit of detection was 1.0×10-11 g,and the limit of quantification in orange and soil was 0.05 mg/kg.The average fortified recoveries varied from 70.8% to 104.1% and relative standard deviation varied from 4.7% to 12.3% when nitenpyram was spiked at 0.05-2 mg/kg level in various matrixes.The study of residue dynamics indicated that the decline curve accorded with the first-order kinetics equation,and the half-life of nitenpyram in orange and soil were 3.4-10.7 d and 1.8-5.4 d,respectively.