Liquid Chromatography Mass Spectrometer (LC-MS/MS) Study of Distribution Patterns of Base Peak Ions and Reaction Mechanism with Quantification of Pesticides in Drinking Water Using a Lyophilization Technique

Abstract

In the process of the development of agriculture, pesticides have become an important tool as an insecticide to kill the insect from plant for boosting food production. Therefore the insecticides/pesticides and herbicides have been used in India for agriculture setting. In this connection a sensitive method for the quantification of 5 pesticides in drinking water samples to the µgL–1 level has been developed. The paper also describes the effect of dissociation energy on ion formation and sensitivity of pesticides in water samples. The structure, ion formations, distribution of base peak and fragmentation schemes were correlated with the different dissociation energies. The new ion was obtained at different mass to charge ratio, which was the characteristic ion peak of targeted pesticide. Additionally, a simple solvent lyophilization followed by selective analysis using a liquid chromatography-mass spectrometry method was used. This method was accurate (≥98%) as it possesses limits of detection in the 6 - 38 ngL–1 range, and the percentage relative standard deviations are less than 8.62% at the low µgL–1 end of the method’s linear range. The percentage recovery of all the pesticides at the 0.1 µgL–1 levels of detection ranges from 92% - 104%. This method was used for the quantification of pesticides in water samples collected from different parts from urban city of Hyderabad, India. In this study, 13 water samples were analyzed in which all samples showed detectable level of the malathion and alachlor. The concentration of pesticides ranged from 0.004 µgL–1 to 0.691 µgL–1 exceeded to the maximum residual limit of Indian standard.