Simultaneous determination of neutral, basic and acidic pesticides in aquatic environmental matrices by solid-phase extraction and liquid chromatographyelectrospray ionization mass spectrometry

Abstract

Simultaneous determination of a wide variety of pesticides and herbicides in environmental waters by liquid chromatography electrospray-ionization mass spectrometry (LC-ESI-MS) has been a challenging task due to matrix interferences. In this study, deuterated analogues and graphitized carbon black (GCB) solid-phase extraction (SPE) were investigated to compensate for and eliminate sample matrix interferences. Significant ion suppression and enhancement were observed when deuterated pesticides were used as internal standards. GCB cartridges can well retain neutral, basic and acidic pesticides and herbicides but the complete elution requires a combination of different characteristics of the solvent. A new procedure for SPE extraction and sample preparation was developed for simultaneous determination of neutral, basic pesticides and phenoxy acid herbicides in environmental waters by LC-ESI-MS. The proposed method was validated by examining the limit of detection and range of linearity and testing river water samples. The limit of detection ranged between 0.005 and 2 μg L⁻¹ and the correlation coefficient for 5–5000 μg L⁻¹ calibration standards was greater than 0.995. The recoveries of 79–121% from river water samples and relative standard deviations of 2–21% were obtained at the concentrations of 0.4–500 μg L⁻¹ for 37 pesticides and herbicides.