Aldoxime-Derived Water-Soluble Polymer for the Multiple Analyte Sensing: Consecutive and Selective Detection of Hg2+, Ag+, ClO–, and Cysteine in Aqueous Media

A simple tailor-made aldoxime-functionalized water-soluble polymeric probe (P-Oxime) for the consecutive colorimetric sensing of multiple analytes, including Hg2+, Ag+, ClO–, and cysteine, was designed and synthesized. A reaction between the aldehyde groups of the side chain in the polymer (P-CHO) and hydroxylamine in ethanol led to the target polymer, P-Oxime. This water-soluble polymeric probe exhibited excellent sensitivity and selectivity toward Hg2+ ions under pH = 5 in water due to the formation of strong electron-withdrawing nitrile groups (P-CN) via Hg2+-promoted dehydration reaction. The high selectivity and sensitivity of P-Oxime toward ClO– over other reactive oxygen species at pH = 9.5 in water were also observed. After the addition of ClO–, the color of the P-Oxime solution turned from pale yellow to red due to the formation of an aldehyde group. By taking advantage of the formation of functional groups during the Hg2+ and ClO– sensing process, the consecutive sensing/binding studies toward t...