Ion-Selective Electrodes for Mercury Determination at Low Concentrations: Construction, Optimization and Application

Potentiometric studies are presented here on solid contact ion-selective electrodes, based on neutral carriers comprising structural sulfur−donating groups and an aliphatic chain, where the latter confers stability to the molecule for the formation of metal complexes. As result, an ISE was obtained for the potentiometric determination of mercury. This sensor allowed continuous mercury determinations at nanomolar levels within a wide concentration interval (1.0 × 10−9 to 1.0 × 10−1) molL−1, with a detection limit of (9.1 ± 0.8) × 10−10 molL−1 and a Nernstian response of (29.8 ± 0.4) mV decade−1. This ISE can be used in the 0–6 pH interval, exhibiting a high selectivity toward the mercury ions even in the presence of interferents, and be used as an indicating electrode during potentiometric mercury titration with EDTA, because it is comparable with the commercial electrodes, within its same class. The main advantage of the ISE reported here is its nM LOD and that it does not require an internal reference.