Highly selective sensing of mercury (II) by development and characterization of a PVC-based optical sensor

A novel optical sensor that is highly selective to Hg2+ ions is described. This is based on the use of 4-phenyl-2,6-bis(2,3,5,6-tetrahydrobenzo[b][1,4,7]trioxononin-9-yl)pyrylium perchlorate as an ionic carrier in a plasticized poly(vinyl chloride) membrane. The sensing membrane is capable of determining mercury(II) with a high selectivity over a wide dynamic range between 2.95 × 10−10 and 3.20 × 10−3 M at pH 5.0 with a lower detection limit of 1.01 × 10−10 M. Validation of the assay method reveals excellent performance characteristics, including long life span, good selectivity for Hg2+ ions over a wide variety of other metal ions, long-term response stability, and high reproducibility. Applications for direct determination of mercury in samples including dental amalgam, shaft water, and fountain give results with good correlation with data obtained using cold vapor atomic absorption spectrometry.