DETERMINATION OF TRACE AMOUNTS OF LEAD BY ADSORFTIVE CATHODIC STRIPPING VOLTAMMETRY WITH L-3-(3,4-DIHYDROXYPHENYL)ALANINE

摘要

A sensitive and selective procedure is presented for the voltammetric determination of lead. The procedure involves an adsorptive accumulation of lead L-3-(3,4-dihydroxyphenyl)-alanine (LDOPA) on a hanging mercury drop electrode, followed by a stripping voltammetric measurement of reduction current of an adsorbed complex at -0.15 V (vs Ag|AgCl). Optimum conditions for lead analysis include pH 8.5, 80 μm LDOPA and accumulation potential -0.15 V (vs Ag|AgCl). The peak currents are proportional to the lead concentration 1-300 nmol l~(-1) with a detection limit of 0.6 nmol l~(-1) and accumulation time 60 s. The method was used for the determination of lead in blood, dry tea and also in waters.