A Novelty in Potentiometric Stripping Analysis: Total Replacement of Mercury by Bismuth

A novel approach of the potentiometric stripping analysis is presented based on total substitution of mercury by bismuth. First, bismuth(III) salts may be applied to form bismuth films and, as confirmed here, these films can be generated also on such supports like carbon paste electrodes. Secondly, bismuth(III) salts may substitute mercury(II) in its role of an oxidant. This offers quite new possibilities of an attractive use of “mercury-free”, environmentally friendly PSA procedures for determinations of some heavy metals. For lead, the method utilizing bismuth for coating the carbon paste surface as well as chemical oxidant offers a detection limit of about 2×10−9 mol/L (ca. 0.5 ppb) when using preconcentration time for 10 min.