New Simple and Rapid Spectrophotometric Methods for the Determination of Trace Level Gold(iii) Using 2,2',3,4-Tetrahydroxy-3'-Sulpho-5'-Chlorazobenzene Presence of the Cationic Surfactants

Abstract

It is shown that gold(III) with 2,2',3,4-tetrahydroxy-3'-sulpho-5'-chlorazobenzene (TSXAB) the rapid reacts in pH 5-6 acidic solution to form brownish-yellow complex and in pH 4-5 acidic solution to form brownish complexes in the presence of the cationic surfactantscetylpyridinium chloride (CPCl), cetylpyridinium bromide (CPBr) and cetyltrymethylammonium bromide (CTMABr). The absorption spectra of the Au(III)-TSXAB system is a curve with the maximum absorbance at 490 nm and molar absorption coefficient of 2.3 . 10 4 l mol −1 cm −1 in aqueous media. The absorption spectra of the Au(III)-TSXAB-CPCl, Au(III)-TSXAB-CPBr and Au(III)-TSXAB-CTMABr systems is a curves with the maximum absorbances at 520, 520 and 540 nm and molar absorption coefficients of 3.78 . 10 4 , 3.67 . 10 4 and 3.81 . 10 4 l mol −1 cm −1 in micellar media respectively. The absorbance was linear for 0.584-5.61 mkg/ml of Au(III) in the Au(III)-TSXAB-CPCl, Au(III)-TSXAB system and 0.428-6.362, 0.435-6.221, 0.436-6.832 mkg/ml of Au(III) in the Au(III)-TSXAB-CPCl, Au(III)-TSXAB-CPBr and Au(III)-TSXAB-CTMABr systems, respectively. The Sandell's sensitivity for Au(III) were found to be 7 mkg cm -2 in Au(III)-TSXAB system and 5, 6, 5 mkg/cm in the Au(III)-TSXAB-CPCl, Au(III)-TSXAB-CPBr, Au(III)-TSXAB-CTMABr systems. The proposed methods was successfully used in the determination of Au(III) in several synthetic mixtures. The relative standard deviation (n = 5) was (0-2.0)%, for Au(III) indicating that this methods are highly precise and reproducible. The results obtained agree well with synthetic mixture samples analyzed by inductively coupled plasma optical emission spectrometry.