Sol–gel derived highly selective optical sensor for sensitive determination of the mercury(II) ion in solution

Abstract

We report a versatile optical sensor by incorporating the indicator dye 4-phenyl-2,6-bis(2,3,5,6-tetrahydrobenzo[b][1,4,7]trioxononin-9-yl)pyrylium perchlorate into a sol–gel layer. The proposed optical sensor that is stable, fast and highly selective to Hg 2+ ions shows a significant absorbance signal change on exposure to an aqueous solution containing mercury(II) ion. The sensing film is able to determine mercury(II) ion in aqueous solution with a high selectivity over a wide dynamic range between 1.52 × 10 −9 and 1.70 × 10 −2 M, at pH 5, and a lower detection limit of 1.11 × 10 −9 M. Validation of the assay method revealed excellent performance characteristics for Hg 2+ ions over a wide variety of other metal ions, including good selectivity, long-term response stability and high reproducibility. Applications, for the direct determination of mercury(II) in real samples, gave the results with good correlation with the data obtained by using cold vapor atomic absorption spectrometry.