Determination of lead in the presence of morin-5'-sulfonic acid and sodium dodecyl sulfate by adsorptive stripping voltammetry.

A simple and sensitive electroanalytical method is developed for the determination of lead by adsorptive stripping voltammetry (AdSV) in the presence of morin-5'-sulfonic acid (MSA) and sodium dodecyl sulfate (SDS). The Pb-MSA complex accumulates on the surface of a hanging mercury drop electrode (HMDE) and peak current is measured by square wave voltammetry (SWV). The complex is reduced at -0.48 V and peak current increases when low concentrations of SDS are added to the sample solution. The experimental variables pH, MSA concentration (C(MSA)); accumulation time (t(acc)); accumulation potential (E(acc)), and SDS concentration (C(SDS)), as well as potential interferences, are investigated. Under the optimized conditions (pH 3.2; C(MSA): 0.5 micromol L(-1); t(acc): 60s; E(acc): -0.35 V, and C(SDS): 20 micromol L(-1)), peak current is proportional to the concentration of Pb(II) over the 0.1-32.0 microg L(-1) range, with a detection limit of 0.04 microg L(-1). The relative standard deviation for a solution containing 5.0 microg L(-1) of Pb(II) solution was 1.5% for seven successive assays. The method was validated by determining Pb(II) in synthetic sea water (ASTM D665) spiked with ICP multi-element standard solution and in certified reference water (GBW08607). Finally, the method was successfully applied to the determination of Pb(II) in tap water and sea water after UV digestion.