Novel All-Solid-State Potentiometric Sensor for Monitoring Hg2+ in Waste Water Samples

A novel all-solid-state (ASS) potentiometric poly vinyl chloride (PVC) membrane sensor is introduced, and to evaluate its applicability in the analyses of real samples it was used for monitoring of mercury ions in waste water samples. The ASS electrode is composed of a conductive composite of graphite and epoxy resin loaded with multi-walled carbon nanotubes (MWCNTs) acting as intermediary layer between an inner copper wire, and an outer thin PVC membrane which is coated on the conducting transducer. The optimal composition of the outer polymeric membrane was found to be 30% of PVC, 60% of nitro benzene (NB) as a plasticizer, 5% of an ionophore L, 2% of an ionic liquid, and 3% NaTPB. The resulting sensor showed a good Nernstian response of 29.4±0.3 mV/decade, in a rather wide range of 1.0×10-8-1.0×10-3 M of the mercury concentration and its detection limit was found to be as low as 3.2×10-9 M. The proposed electrode was also found to have good selectivity towards the target ion in the presence of a wide range of commonly occurring ionic species and was further used to determine the concentration of Hg2+ ions in waste water samples