Possible mercury speciation in urine samples using potentiometric methods

The strong dependence of heavy metal toxicity on metal physical–chemical structure has directed the interest in the qualitative and quantitative measurement of metal species in different environments. Mercury is ubiquitous in the environment, and occurs in three oxidation states in several physical and chemical forms. Among these, Hg(II) can severely damage the kidneys and the gastrointestinal tract, and is generally a serious hazard to human health. Potentiometric sensors based on ion-selective electrodes provide a simple, highly selective, precise, and economical method for online Hg(II) concentration monitoring in a variety of environments. Due to their selectivity, neutral carrier-based potentiometric sensors are routinely used for measuring ions directly in complex biological and environmental samples, and therein, several Hg(II)-selective electrodes have been studied in literature. This work presents a Hg(II) ion-selective electrode that uses a 1,4,8,11-tetrathiacyclotetradecane derivative entrapped inside a membrane for the measurement of Hg(II) in urine samples. Alumina modified dimethyl sulfoxide (AMDMSO) was used to separate Hg(II) from matrices, a mechanism already suggested in literature explaining the unique uptake of Hg(II) ions by binding as neutral at pH values < 3.