Coprecipitation of lead and cadmium using copper(II) mercaptobenzothiazole prior to flame atomic absorption spectrometric determination

A coprecipitation method using a combination of 2-mercaptobenzothiazole (MBT) as a chelating reagent and copper as the coprecipitate carrier is described for the determination of trace lead and cadmium by flame atomic absorption spectrometry. The coprecipitation conditions, such as the effect of pH, the amount of carrier element and reagent, standing time, sample volume and matrix effects were examined in detail. It was found that lead and cadmium are coprecipitated quantitatively ( >= 95%) with Cu( II)MBT at pH 9 and that the relative standard deviations (n = 7) were <= 1.6%. When using the enrichment factors of 150-fold for lead and cadmium, the detection limits (3s/b) obtained are 1.08 for lead and 0.04 mu g L-1 for cadmium. The method was validated with spiked sea water, stream water, well water, and vegetable samples.