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

It is shown that gold(III) with 2,2',3,4-tetrahydroxy-3'-sulpho-5'-chlorazobenzene (TSXAB) the rapid re-acts 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 surfactants – cetylpyridinium 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 2.3.104 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 3.78.104, 3.67.104 and 3.81.104 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