A Novel Application of Natural Peat for Solid-Phase Extraction of Pyrimethanil, Flumetralin, and Kresoxim-Methyl in Water Using Gas Chromatography-Mass Spectrometry

Natural peat was tested for extraction of pyrimethanil, flumetralin, and krexosim-methyl from water, with analysis using gas chromatography-mass spectrometry (GC-MS) in selected ion monitoring mode (SIM). Experiments were carried out at one fortification level (0.1？μg？L？1) and resulted in recoveries in the range 41–96%, with RSD values between 6.8 and 12.6% for natural peat as sorbent. Detection and quantification limits ranged from 0.02 to 0.05？μg？L？1 and from 0.07 to 0.1？μg？L？1, respectively, for the different pesticides studied. The method developed was linear over the range tested (0.07–4.0？μg？L？1), with correlation coefficients ranging from 0.9919 to 0.9989. Comparison between peat and commercial sorbents (C18-bonded silica, ENVI-Carb, Florisil, silica gel, ENVI-Carb/LC-NH2) showed better performance of peat sorbent for flumetralin and kresoxim-methyl. 1. Introduction In recent years, research into new materials for the extraction and purification of organic compounds has also been stimulated by the growing interest in environmental preservation and human health protection [1, 2]. In view of this, natural peat is a sedentarily accumulated material consisting of dead organic matter in the waterlogged environment. Due to the high content of humic substances, natural peat exhibits favorable physicochemical properties enabling the application in various technical areas, for instance, wastewater treatment, pollution monitoring, fuel production, soil fertilizing, and veterinary and human medicine [3]. Peat, as an adsorbent, is a porous material with highly polar character because it carries polar functional groups such as alcohols, aldehydes, carboxylic acids, ketones, and phenolic hydroxides, which can adsorb large quantities of metals, dyes, and other organic molecules, whose adsorption capacity is comparable to conventional extracting phase like activated carbon, silica gel, or alumina [4, 5]. However, no studies of the use of peat material for solid-phase extraction of pesticides in water have been reported. For the control of level concentration of pesticide residues in water, the Ministry of Health in Brazil established the value maximum allowable by decree number 518 on March 25, 2004 [6]. For environmental and drinking water, the maximum admissible concentration of a single compound established by the European Union (EU) is 0.1？μg？L？1, and 0.5？μg？L？1 is the maximum allowed for the total concentration of all pesticides [7, 8]. The aim of this study was to evaluate the performance of the natural peat as an alternative sorbent for the solid-phase