Multi-Residual Determination of Multi-Class Pesticides in Groundwater by Direct Immersion Solid-Phase Microextraction with Gas Chromatography-Selected Ion Monitoring Mass Spectrometry (GC–MS/SIM) Detection

Elizarragaz-de la Rosa, Dalaú; Guzmán-Mar, Jorge Luis; Salas-Espinosa, Edgar Arturo; Heras-Ramírez, María Elena; Hinojosa-Reyes, Laura; Gaspar-Ramírez, Octavio; Ruiz-Ruiz, Edgar Jocsan

Multi-Residual Determination of Multi-Class Pesticides in Groundwater by Direct Immersion Solid-Phase Microextraction with Gas Chromatography-Selected Ion Monitoring Mass Spectrometry (GC–MS/SIM) Detection

2022

This paper describes a simple, quick, and solvent-free multi-residue method to determine 90 pesticides in groundwater samples from 30 different chemical groups. The extraction was carried out by solid-phase microextraction in direct immersion mode (DI-SPME) using a polydimethylsiloxane/divinylbenzene fiber (65 µm thickness) followed by GC–MS detection. The main parameters affecting the DI-SPME process were studied in detail: temperature, NaCl addition, stirring rate, and extraction time. The validation parameters as linearity, precision (repeatability and reproducibility), and accuracy were evaluated. The limits of quantification (LOQs) were in the range of 0.009–0.976 µg L⁻¹. The analytes recoveries in groundwater samples varied from 60 to 120% and were appropriate for this type of water. The validated analytical method was successfully applied to the analysis of groundwater from wells located in agricultural sites in the municipality of Cadereyta Jimenez in Nuevo Leon, Mexico. The pesticides p, p’-DDT, bifenthrin, 2,4’-D ethylhexyl ester, and aldrin were below the LOQs in 73% of the analyzed samples. Oxyfluorfen and fenoxycarb were quantified at 0.08 and 0.2 µg L⁻¹, respectively. Fenoxycarb was above the maximum allowable concentration of 0.1 µg L⁻¹ for drinking water established by the European Union.

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