Extraction of some pesticides from grape juice samples using an amide-based polymer as a sorbent followed by gas...

A sensitive and efficient analytical method based on dispersive micro solid phase extraction combined with dispersive liquid-liquid microextraction followed by gas chromatography-flame ionization detection was developed for the determination of haloxyfop-R-methyl, oxadiazon, diniconazole, tebuconazole, and difenoconazole in grape juice samples. An organic polymer was synthesized through a facile polyamidation reaction of benzene-1,3,5-tricarboxylic acid and ethylenediamine and employed as an efficient sorbent. The synthesized material was characterized by routine analyses. Key parameters affecting both extraction steps were systematically optimized. Under optimum conditions, the method showed limits of detection between 2.0 and 2.58 µg L^-1, limits of quantification of 6.6-8.51 µg L^-1, and wide linear ranges up to 6000 µg L^-1 with excellent coefficients of determination (r ² = 0.9971-0.9990). High enrichment factors (365-495) and extraction recoveries (73-99%) were obtained with good precision (intra- and inter-day relative standard deviations ≤ 4.42%). Matrix effect evaluation in real grape juice samples revealed negligible interference, with relative recoveries in the range of 88-119%. In addition, the sorbent demonstrated acceptable reusability over four consecutive extraction cycles (RSD ≤ 15%). The proposed method provided a simple, cost-effective, and reliable approach for the determination of pesticide residues in complex beverage matrices.