Use of gold nanoparticle-coated sorbent materials for the selective preconcentration of sulfonylurea herbicides in water samples and determination by capillary liquid chromatography

Two new gold nanoparticle (NP) coated materials (silica supported on gold NP with and without ionic liquid) were synthesized for solid phase extraction of sulfonylurea herbicides (SUHs), such as bensulfuron-methyl (BSM), metsulfuron-methyl (MSM), pyrazosulfuron-methyl (PSM), thifensulfuron-methyl (TFM) and triasulfuron (TS), from water samples, followed by capillary liquid chromatography coupled to diode array detection (CLC–DAD). Several factors influencing the preconcentration efficiency of SUHs and its subsequent determination, such as pH of the sample, eluent and reusability of sorbents, have been investigated. Under the optimum conditions, the developed method allowed the determination of BSM, MSM, PSM, TFM and TS in a linear range between 0.05 and 1.00 μg mL−1, with relative standard deviation values lower than 4.5% (n=10), in all cases. Detection limits within 0.002–0.009 μg mL−1 range were achieved. The usefulness of the proposed method was demonstrated by the analysis of river water samples, in which recoveries between 83.9 and 105.0% were obtained. The Au–NP-ionic liquid-functionalized silica sorbent showed higher recoveries (selectivity) for the SUHs than the commercially available C18 sorbents.