Spectrophotometric method for the determination of trace amounts of mercury: Application to environmental and biological samples

A method for the determination of mercury in environmental and biological s amples, has been developed. The method is based on the complexation reactio n between mercury and 4-(-2-benzothiazolylazo) 2,2 biphenol (I), 5-(-2-benz othiazolylazo)-8-hydroxyquinoline (II),1-(2-benzothiazolylazo)2,3-naphthale ne diol (III) and 8-(2-benzothiazolylazo) 1,4-naphthalenediol (IV). The pot entiality of the prepared compounds as new chromogenic reagents for the spe ctrophotometric determination of mercury ions are studied by extensive inve stigations of the optimum conditions favouring the formation of the coloure d complexes. The method allows the determination of Hg2+ in the range of 0. 1- 6.5, 0.1-7.2, 0.1-4.8 and 0.1-6.5 mu g ml(-1) at wavelengths 590, 629, 6 06 and 591 nm on using reagents I, II, III and IV, respectively. The detect ion limits (3 sigma) are 0.01 mu g ml(-1) for all studied reagents. The mol ar absorptivity and Sandell sensitivity are also calculated. The effect of various interfering ions and their tolerance limits has been studied. The c onditions developed were used successfully for the determination of Hg2+ io ns in environmental and human (urine and blood) samples.