Effectiveness of Water Hyacinth Biochar as a Potential Adsorbent in Solid-Phase Extraction Together with Liquid Chromatography-Mass Spectrometry for Determination of Pesticide Residues in Lager Beer

In this work, we present the development and validation of an extraction analytical method for determination and quantification of 18 pesticides belonging to the chemical classes of benzimidazoles, organophosphates, anilides, triazoles, avermectins, benzoylureas, triazines, pyrethoids, neonicotinoids, and strobilurins in industrial samples of larger beer, employing solid-phase extraction (SPE), ultra-performance liquid chromatography-mass spectrometry. The optimized SPE procedure employed 100 mL of sample, 150 mg of biochar adsorbent, and elution with 3 mL of methanol:dichloromethane (60:40, v/v), resulting in a fast, practical, and economical technique. The methodology showed good linearity (R² > 0.99). The average recoveries (n = 5) for the lowest concentration level ranged from 61 to 102%, with relative standard deviations between 2 and 19%. Detection and quantification limits ranged from 0.05 to 0.08 µg/L and from 0.01 to 0.25 µg/L, respectively. In addition, the method was applied to 13 commercial Pilsen-type larger beer labels, in which pesticide residues were not found.