Voltammetric determination of trace mercury in concentrated chloride media using polymer-film electrodes modified with polyammonium macrocyclic receptors

Abstract

Trace amounts of mercury can be determined voltammetrically in aqueous solution on Paraloid B72 film electrodes modified by the macrocyclic polyamine receptors 1,4,7,10,13,16,19,22,25,28-decaazacyclotriacontane and 1,4,7,10,13,16,19,22,25,28,31-undecaazacyclotritriacontane. These receptors are able to form very stable mono-, bi-, and trinuclear complexes with Hg²⁺ ions in the pH range 3–12, favouring the preconcentration step. Very stable Cl^––macrocycle mixed complexes with Hg²⁺ are also formed, allowing the determination of mercury traces in large concentrated chloride media. Under optimized conditions, this procedure gives good linearity for nanomolar mercury concentrations and a detection limit of 0.2 × 10^–10 mol L^–1. Results concerning the optimization of the method and lowering of the influence of possible interferents are reported.