Highly sensitive potentiometric sensor for detection of mercury in Cl−-rich samples

• A sensitive potentiometric sensor for detection of HgCl3− is reported.
• Lead ionophore IV is used as the ion carrier for the anionic chloro-mercury complex.
• The asymmetric membrane configuration is employed to improve the sensor sensitivity.
• The proposed method allows for potentiometric detection of mercury in Cl−-rich media.

Potentiometric sensors have been exploited for the determination of Hg2+ ions. However, applications of such sensors are limited to mercury detection in the absence of a Cl−-rich background since Hg2+ can readily form coordination complexes with Cl−. This paper describes a potentiometric sensor for the determination of anionic mercury species using tert-butylcalix[4]arene-tetrakis(N,N-dimethylthioacetamide) as anion-selective ionophore and tridodecylmethylammonium chloride as ion exchanger. An asymmetric membrane rotating ion-selective electrode configuration is used to improve the detection sensitivity. By using HgCl3− as a model of anionic mercury species, the proposed method allows potentiometric detection of mercury down to nanomolar levels in samples containing 0.05 M NaCl background electrolyte. The practical application of the proposed sensor has been performed for the determination of total mercury concentrations in diluted seawater samples.