Abstract
Two novel potentiometric sensors that are highly selective to Hg2+ ions are described. These are based on the use of 5,5′-dithio-bis(2-nitrobenzoic acid) (DTNB) and tricyclazole (TCZ) as neutral carriers in plasticized poly(vinyl chloride) membranes. Fast Nernstian responses are obtained for Hg2+ ions over the concentration ranges 7.0 × 10-6 - 1.0 × 10-2 and 7.7 × 10-6 - 1.0 × 10-2 mol l-1 at pH 1.8 - 3.3 with lower detection limits of 5.0 × 10-6 and 5.6 × 10-6 mol l-1 (∼1 µh ml-1) and calibration slopes of 30.0 and 29.7 mV decade-1 with DTNB- and TCZ-based membrane sensors, respectively. Validation of the assay method reveals good 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 hazardous wastes including dental amalgam, mercury bulbs, and fluorescent lamps give results with good correlation with data obtained using cold vapor atomic absorption spectrometry.
