Anodic stripping voltammetric determination of traces of mercury with a chemically modified electrode

Abstract

A new method for the determination of traces of mercury(II) with a ferrocenoylpolythia crown ether—Nafion-modified glassy carbon electrode was developed. The modified electrode was formed by simply adding the desired amount of modification solution onto the glassy carbon electrode surface and drying in air. The mercury ion is accumulated on the modified electrode surface by the complexing effect of the modifier during the electrochemical deposition. After medium exchange, the accumulated mercury is determined by the anodic stripping voltammetric method. A linear response of the stripping peak current with concentration is observed for 3 × 10 −9 −8 × 10 −8 M of mercury(II) and the detection limit is 1 × 10 −9 M (5 min preconcentration period). High sensitivity is obtained owing to the complexing effect of the modifier and the release of the complexing reagent (modifier) from the mercury(II) complex during the electrochemical deposition. For 10 deposition/determination cycles (1 × 10 −8 M Hg(II)) the response could be reproduced with a 3.8% relative standard deviation. Many parameters such as the composition of the modification solution, concentration of electrolyte, electrodeposition potential etc., influence the response of the determination. The effect of coexisting ions has been examined. The procedure has been applied to the determination of mercury in hair, water, and urine samples.