Quaternary ammonium pesticides: A review of chromatography and non-chromatography methods for determination of pesticide residues in water samples

The monitoring of pesticide residues in water sources is essential because of their increased worldwide demand in agriculture and their subsequent detection in waters. Pesticide residues in water matrices are traditionally determined by multiresidue methodologies based on chromatography coupled to mass spectrometry. However, for quaternary ammonium pesticide residues, as highly polar compounds, the chromatographic approach frequently fails, requiring modifications in the separation method, or even an alternative technique for analyte quantification. Therefore, to solve this analytical limitation for these residues, several authors proposed unusual methodologies, such as those based on spectroscopic or electroanalytical approaches. This review intends to offer an overview of the analysis of quaternary ammonium pesticide residues in different water sources, focusing on advances in sample preparation before chromatographic separations and alternative analytical techniques, such as spectroscopy and electroanalytical methods.