A Multiresidue Method for the Analysis of Pesticides in Water using Solid-Phase Extraction with Gas and Liquid Chromatography-Tandem Mass Spectrometry (ver. 2.0, April 2023)

Applications of pesticides in agricultural and urban settings play an essential role in increasing crop yields, preserving food and materials, reducing pest-borne diseases, and eradicating or deterring pests. Pesticides are transported from their point of application to environmental media, including surface water. To better understand the fate of fate and transport of pesticides in the environment, analytical methods are necessary to measure pesticides in waters. Herein, a method is described for the extraction and analysis of pesticides and pesticide degradates in filtered surface water and paired suspended sediment samples. Water samples (~ 1 L) are filtered using 0.7 μm glass-fiber filters prior to being extracted and concentrated using hydrophilic-lipophilic balance (HLB) cartridges. Suspended sediment samples are extracted via ultrasonication, solid-liquid extraction. Analyses are completed using liquid chromatography tandem mass spectrometry (LC-MS/MS) and gas chromatography tandem mass spectrometry (GC-MS/MS). Initial analyte recoveries in surface water samples spiked at 50 ng/L (n = 3) ranged 59.5-109% with an average recovery of 89.2%. The average relative standard deviation (RSD) was 4.9%. Calculated limits of detection (LODs) and reporting limits (RLs) from LODs ranged 0.5-10 ng/L and 1.5-30 ng/L, respectively. Analyte recoveries, method detection limits (MDLs), and RLs from MDLs were determined for surface water and suspended sediment following fortification of samples at 15 ng/L (n = 9). Recoveries were 70.1-121% in water and 71.1-117% in suspended sediment, with average recoveries of 87.0% and 85.5%, respectively. The method showed great reproducibility with an average RSD of 3.8% in water and 5.5% in suspended sediment. MDLs and RLs in water ranged 0.5-10.6 ng/L and 1.1-21.1 ng/L, respectively. In suspended sediment, MDLs ranged 0.7-11.8 ng/L and RLs ranged 1.5-23.7 ng/L. The analytical method will be applied toward the analysis of pesticides and degradates in surface water samples from around the United States.