A direct spectrophotometric method for the determination of mercury in environmental and biological samples using p-carboxybenzenediazoaminobenzene-p-azobenzene

A very simple, sensitive and highly selective spectrophotometric method for the determination of mercury in biological and environmental samples described herewith is based on the formation. of orange coloured species of Hg-II with p-carboxybenzenediazoaminobenzene-p-azobenzene (CDABAB) and a non-ionic surfactant TX-100 over pH range 9.4-10.6. The orange colored Hg-II-(TX-100)-(CDABAB) complex in aqueous medium shows maximum absorbance at 510 nm with molar absorptivity value of 7.9 x 10(4) dm(3) mol(-1) cm(-1). The detection limit of the method is 6 ng ml(-1). The system obeys Beer's law up to 2.0 mu g Hg-II ml(-1) in aqueous phase. The repeatability of the method was checked by finding relative standard deviation (RSD, n = 10) value for solutions each containing 1.0 mu g Hg-II ml(-1) and RSD value of the method was found to be 1.5%. The validity of the method has been satisfactorily examined for the determination of mercury in biological and environmental samples. The RSD value for the actual analyte content ranged between 2.1 to 2.7%.