Separation and preconcentration of trace amounts of gold from water samples prior to determination by flame atomic absorption spectrometry

A preconcentration/separation procedure is presented for the solid phase extraction of trace gold(III) as its rubeanic acid (dithiooxamide) chelate on silica gel, prior to determination by flame atomic absorption spectrometry. The influences of analytical parameters including pH of the aqueous solution, the amount of the sorbent, time of the complex formation, ligand amount, flow rates of sample and elution solutions and the type, concentration and volume of elution solution on the quantitative recoveries of Au(III) were investigated. At pH 3.5, the maximum sorption capacity of Au3+ was 7.5 mg g(-1), by column method. The linearity was maintained in the concentration range of 1.0-3.4 x 10(4) ng mL(-1) for gold in the original solution. The preconcentration factor of 100 and relative standard deviation of +/- 1.7% were obtained, under optimum conditions. The limit of detection (LOD) was calculated as 0.80 ng mL(-1), based on 3 sigma(bl)/m (n=8) in the original solutions. The proposed method was successfully applied to the determination trace amounts of gold in the water samples. (C) 2012 Production and hosting by Elsevier B.V. on behalf of King Saud University.