Potentiometric stripping analysis of traces of thallium(III) at a poly(4-vinylpyridine)/mercury film electrode

The application of potentiometric stripping analysis (PSA) to the trace determination of thallium(m) at a poly(4-vinylpyridine)/mercury film electrode (PVP/MFE) is demonstrated. Thallium(III) is preconcentrated as the anionic form, [TlCl4](-), by the ion-exchange effect into the PVP/MFE. The high solubility of thallium in mercury subsequently helps to increase the accumulation effect. The variable factors influencing the PSA response are thoroughly explored and optimized. The PVP/MFE shows good resistance to interferences from surface active compounds and common ions with an excellent sensitivity by PSA over square-wave voltammetry (SWV). With 1 min of accumulation time, the calibration plot was found to be linear up to 100 ppb with a detection limit of 0.064 ppb (S/N= 3). The analytical utility was demonstrated by application to various water samples.