Determination of Cd, Co, Hg, and Ni in seawater after enrichment on activated carbon by slurry sampling electrothermal AAS

Abstract

An enrichment of trace metals using the activated carbon method was investigated for the preconcentration of Cd, Co, Hg, and Ni in seawater after complexing with 150 mg mL-1 8-hydroxyquinoline, pH 6-10. The adsorbed activated carbon was prepared as a slurry in glycerol or in boiled tapioca suspension before electrothermal atomic absorption spectrometric measurement. A contact time of 5 minutes was adequate for quantitative adsorption. Slurry concentration between 1-10 % could be used. An enrichment factor of up to 20,000-fold was achieved, with recoveries ranging from 84-114%. At 3% slurry concentration, the detection limits for Cd, Co, Hg, and Ni in seawater were 0.0003, 0.007, 0.12 and 0.007 ng mL-1, respectively.