Spectrophotometric determination of cadmium using thiazolylazo chromogenicreagents in the presence of triton X-100: Application in environmental samples

A highly sensitive, selective, and accurate spectrophotometric method for t he determination of cadmium using some thiazolylazo (I-V) chromogenic reage nts has been developed. In the presence of Triton X-100 and NH3/NH4Cl buffe r solutions, the optimum conditions for complexation, stoichiometric ratio, and stability constants are studied. Beer's law is obeyed up to at least 4 .4 mug/10 ml of cadmium. A limit of detection and quantifications of 0.96 a nd 3.3 ng ml(-1) have been estimated and a coefficient of variation of 1.9% at the 3.0 mug level was found. The molar absorptivity and Sandell sensiti vity for each reagent are calculated. The only species that interfere serio usly are Hg2+ and Ni2+. The method has been applied to determine cadmium in water samples, and plant materials, and compared statistically with the AA S method. Interferences were overcome by using mixed masking agents and pre liminary extraction into Aliquat 366/carbon tetrachloride.