Analysis of dialkyl urine metabolites of organophosphate pesticides by a liquid chromatography mass spectrometry technique

A sensitive method for the quantification of six dialkyl phosphate (DAP) urinary metabolites (DMP, DEP, DMTP, DETP, DMDTP, and DEDTP) in urine samples at ng mL−1 concentrations was developed. A solvent extraction followed by selective analysis by a liquid chromatography-mass spectrometric method was used. This method was found to be very accurate and exhibited the limits of detection as follows: DMP, 0.058 ng mL−1; DEP, 0.009 ng mL−1; DMTP, 0.004 ng mL−1; DETP, 0.0148 ng mL−1; DMDTP, 0.00861 ng mL−1; and DEDTP, 0.0198 ng mL−1. The limits of quantification were in the range of 0.0287 ng mL−1 to 0.0743 ng mL−1. The value of the coefficient was found to be ≥0.999 for all of the metabolites. The percent recovery of the pesticides, at the lowest levels of detection, ranged from 93–107% and the coefficient variation was found in the range of 0.400–7.98, which indicates high degree of accuracy and precision. This method is found to be more cost-effective because the quantity of chemicals involved is much less compared with other methods. This method is also found to be simple because the number of steps where there was a chance of sample spillage were reduced, and it can also be used for quantification of pesticide concentrations in urine samples collected from the general population throughout various parts of the world. Initially, 30 samples were analyzed, and the mean concentration of the metabolites ranged from 0.058 to 118.27 ng mL−1, which suggests that the children of Hyderabad city were exposed to OP pesticides.