A liquid chromatography with tandem mass spectrometry method to simultaneously determinate chlorpyrifos, imidacloprid and imidacloprid metabolites in wheat

A liquid chromatography with tandem mass spectrometry method was developed and validated to simultaneously determine chlorpyrifos, imidacloprid, and imidacloprid metabolites in soil, wheat grain, and wheat straw matrices. Satisfactory linearity (R-2 >= 0.9965) of the method was obtained for all analytes. The ranges of limits of detection and limits of quantification for seven analytes in three matrices were 0.17-66.7 and 0.5-200 mu g/kg, respectively. Average recoveries were 72.85-81.25% for chlorpyrifos, 78.54-84.70% for imidacloprid, 73.83-81.03% for imidacloprid olefin, 71.47-80.61% for 5-hydroxy imidacloprid, 71.79-81.32% for imidacloprid urea, 70.42-82.20% for imidacloprid nitroguanidine, and 70.91-82.46% for imidacloprid 6-chloronicotinic acid in soil, wheat grain, and wheat straw. The intra-and interday relative standard deviations were less than 8%. The established method was successfully applied for the residual analysis of chlorpyrifos, imidacloprid, and imidacloprid metabolites in actual soil, wheat grain, and wheat straw samples. The results indicated that the established method could be used to detect trace amounts of chlorpyrifos, imidacloprid, and imidacloprid metabolites in wheat and that the method might be able to provide some data on the detection of these seven compounds in other crops.