Pesticide residues in groundwater and surface water: recent advances in solid-phase extraction and solid-phase microextraction sample preparation methods for multiclass analysis by gas chromatography-mass spectrometry

This brief review reports the literature involving analyses of the classes of pesticides in surface water and groundwater with attention to the toxicity of multiclass pesticides (e.g., carbamates, neonicotinoids, organochlorines, organophosphates, and pyrethroids) and the recent advances in the sample preparation methods using solid-phase extraction (SPE) and solid-phase microextraction (SPME). The aim is to clarify different trends and facilitate decision-making by the scientific community in order to carry out further studies in this field. Different countries have different pesticide regulations for the maximum level of residues allowed. A comparative analysis has revealed some of these classes are not studied in depth rather. Comparative studies have also revealed that recent improvements in SPME fibers have made it possible to minimize the instability of pesticides due to the matrix effect and obtaining cleaner extracts. Regarding the detection systems, the tandem MS are preferred as they have high sensitivity and selectivity, although traditional techniques (like single MS and other gas chromatography detectors) are still commonly used due to their accessibility and good sensitivity to some pesticides. Numerous studies have explored the determination of residues of carbamates, organochlorines, organophosphates, neonicotinoids and pyrethroids in water samples using SPE or SPME (commercial and synthetic materials), highlighting their characteristics and modes of operation. Regarding the determination of pesticide residues in aqueous samples by gas chromatography, since pesticides are very susceptible to the matrix effects, it is necessary to use efficient strategies that make the SPME viable to compensate for the matrix effect in complex samples. In this review, statistical tests, matrix matched calibration and correction factor (Cf) with selected surrogate standards have been explored as strategies to guarantee the reliability of the analytical results in the analysis of pesticides in water using SPME.