Eco-friendly trace analysis of silver in beer/wine samples using a new co-polymeric nanocomposite based-ultrasound assisted-cloud point extraction combined with spectrophotometry

Abstract

In this study, a new magnetic nanocomposite based on the tris(2-hydroxymethyl)aminomethane-modified poly(styrene-co-N-maleimide) copolymer and Fe3O4 nanoparticles were prepared as a new micellar interface for pre-concentration of trace levels of silver from aqueous solutions by ultrasound assisted-cloud point extraction (UA-CPE). The structure of the nanocomposite was characterized by using some instrumental tools in detail. The method is selectively based on charge transfer among silver and reagents at pH 5.0, and detection by micro-volume UV–vis spectrophotometry at 346 nm. The main variables affecting extraction efficiency were evaluated and optimized in detail. Under the optimized conditions, the method shows good linear relationships in ranges of 2.5−125 μg L−1 and 4−160 μg L−1 by two calibration curves (established in solvent and beer/wine matrices) with a better determination coefficient (r2) than 0.992. The limits of detection, repeatability/intermediate precision (as RSDs%, 5, 25 and 100 μg L-1, n: 5) and recovery percentages were 0.85/1.21 μg L-1, 3.5–7.1% and 91.5–98.5%, respectively. From pre-concentration of 25-mL sample solution, a pre-concentration factor was found to be 62.5 with sensitivity enhancement of 23.2-fold in calibration. A matrix effect was not observed for the triplicate measurements of 100 μg L−1 Ag+ in the presence of various interfering species. The method accuracy was validated with the outcome of validation that was carried out. The method after two sample preparation procedures was successfully applied to reliable determination of total Ag in beer and wine samples. The total Ag levels were in range of 2.5–4.2 and 2.7–5.5 μg L−1 in beer and wine samples, respectively.