Potentiometric stripping analysis and the speciation of heavy metals in environmental studies

Abstract

Potentiometric Stripping Analysis (PSA) is applied to a wide variety of acidic dissolution reagents to investigate the inherent possibilities of this method in heavy metal speciation studies using various specific extraction media. The nature and the concentration of the acids, pH and ionic strength effects are studied in the pH range 0–6.5 and with ionic strengths ranging from 10 −4 to 5 M. PSA offers serious advantages over other electrochemical methods based on current measurements: the method gives correct analytical signals in a wide pH range (0–6.5) for all types of acidic reagents and in the whole range of ionic strengths. The study is conducted in the goal of permit routine measurements of heavy metal determinations in speciation studies of environmental samples: cadmium, lead and copper ions have been chosen as heavy metal ions and mercury(II +) is the chemical oxidizing agent and the precursor in mercury film formation onto the glassy carbon working electrode.