Determination of fipronil and fipronil-sulfone in surface waters of the Guandu river basin by high performance liquid chromatography with mass spectrometry.
Insecticide, Guandu River, Surface water, LC-MS, Contamination.
Fipronil (FIP) is a broad-spectrum insecticide used in the industrial, residential and agricultural sectors, which poses environmental and human health risks. FIP and its degradation products have been found in a variety of environmental matrices, with fipronil-sulfone (FIP-S) being one of the most commonly found degradation products. In several countries studies have reported the presence of fipronil in aquatic environments. However, its occurrence in surface water in Brazil is limited. Within this context, the objective of this work was to validate an analytical method using solid phase extraction (SPE) and liquid chromatography coupled to mass spectrometry (LC-MS) capable of evaluating the presence of fipronil and fipronil-sulfone in surface water. The method was validated according to INMETRO and USEPA. The proposed method was applied to analyze 16 samples collected during summer and autumn 2020 at sampling points of the Guandu River Basin in Rio de Janeiro State. FIP was the main analyte found in the evaluated samples, with concentrations in the range of 0.132 – 2.44 μg/L. FIP-S was quantified only in one sample (0.135 μg/L), but it was possible to detect the presence of this analyte in most samples. A higher concentration of FIP in surface water was observed in autumn (2.44 μg/L) compared to summer. This is the first study of the occurrence of FIP and FIP-S in the Guandu River Basin. The values are high enough to warrant monitoring studies in a region of great importance for the city of Rio de Janeiro and indicate the need to include this pesticide and its derivatives in water quality legislation.