Quinoxaline-functionalized silver nanoparticles as chromogenic probe for the multiple selective detection of cysteine, Mg2+ and Sn2+ in aqueous solution

Abstract Herein we report the successful synthesis of stable silver nanoparticles (AgNPs) using 1,1′-(quinoxaline-2,3-diylbis(azanediyl))diethanol (QX) as the only stabilizer. The QX-AgNPs system was then employed as chromogenic probe for the selective detection of L -cysteine (Cys), Mg2+, and Sn2+ in the presence of interfering species. We discuss the role of pH for differentiation between Mg2+ and Sn2+ in terms of analyte-induced aggregation mechanisms. Limits of detection reached 2.7 nmol L−1, 15 nmol L−1 and 18 nmol L−1 for Cys, and Mg2+ and Sn2+, respectively, which are levels comparable to other reported probes. Concerning Mg2+, the LOD found in this study was the lowest ever reported. The QX-AgNPs were also successfully employed in the quantification of Cys in urine and Mg2+ in tap water.