Evaluation of calibration approaches for quantification of pesticide residues in surface water by SPE with small-size cartridges followed by fast GC-MS

A fast GC-MS method for analysis of twenty four GC amenable pesticides in surface water was developed and validated. Extraction of pesticides using solid phase extraction (SPE) with small-size cartridges was performed. Four calibration approaches for quantification purposes, (1) acetonitrile (MeCN) standards, (2) MeCN standards with analyte protectants (APs), (3) matrix-matched standards, and (4) matrix-matched standards with APs, were investigated and statistically compared in terms of validation parameters. Linearity was studied in the concentration range of 0.01–2.5 μg L−1 with coefficients of determination (R2) higher than 0.9466. Satisfactory recoveries at three studied concentration levels (0.05, 0.1 and 1 μg L−1) in the range of 65.6–100.3% with relative standard deviation <19% were obtained. The limits of detection (LODs) and limits of quantification (LOQs) were evaluated for all approaches. LODs ranged from 0.06 to 20 ng L−1 and LOQs from 0.2 to 65 ng L−1. The developed and validated method was applied for the analysis of Danube River water samples.