Spectrophotometric Determination of Gold after Separation and Preconcentration with a Solid-Phase Extraction Method

A simple, sensitive, and inexpensive method for separation and preconcentration of gold ions from aqueous solutions prior to its spectrophotometric determination is reported. The proposed method includes two procedures. In the first one, sodium 8-aminoquinoline-5-azobenzene-4'-sulfonate (SPAQ) was immobilized directly on an alumina column which adsorbed gold ions from aqueous Solutions. Then, Au-III was desorbed by HCl solution, and the absorbance of the alkaline solution in the presence of a cationic surfactant, cetyltrimethylammonium bromide (CTMAB), was measured at 611 nm. In the second procedure, Au-SPAQ complex in the presence of CTMAB in alkaline media was passed through the column containing alumina (washed with nitric acid and neutralized by washing with distilled water). The complex was then desorbed with ethanol, and the absorbance was measured immediately at 611 nm. The proposed methods were applied Successfully to the determination of gold in Azerbaijan ores. The relative standard deviations for five replicate determinations of 0.2 mu g mL(-1) Au-III for the first and second procedures were 3.01% and 2.66%, and the corresponding limits of detection were 1.37 and 3.70 mu g L-1, respectively.