Study on the adsorptive stripping voltammetric determination of trace cerium at a carbon paste electrode modified in situ with cetyltrimethylammonium bromide

Abstract

A procedure was developed for the determination of trace cerium based on the oxidation of the absorbed cerium (III)–alizarin complexon (ALC) complex at a carbon paste electrode (CPE) modified in situ with cetyltrimethylammonium bromide (CTAB). Optimum experiment conditions included 2.0 × 10 −6 mol l −1 ALC, 6.0 × 10 −5 mol l −1 CTAB , 0.1 mol l −1 acetic acid and sodium acetate (HAc–NaAc) and 0.2 mol l −1 potassium biphthalate (KHP), pH 5.0, an accumulation potential of −0.1 V, and a scan rate of 100 mV s −1. Linearity between peak currents and concentrations existed for 8.0 × 10 −10 to 8.0 × 10 −9 mol l −1 for 120 s accumulation and 8.0 × 10 −9 to 1.0 × 10 −7 mol l −1 for 60 s accumulation. The detection limit after a 120 s preconcentration was 6.0 × 10 −10 mol l −1 (S/N = 3). The relative standard deviation was 4.9% for eight successive determinations on the same electrode surface at 2.0 × 10 −8 mol l −1 level. The procedure was expected to determine trace cerium with elevated selectivity. The results were quite consistent with the certified values for the determination of cerium in rare earth nodular cast iron samples.