Photoinitiated gold sol generation in aqueous Triton X-100 and its analytical application for spectrophotometric determination of gold

Gold complex, HAuCl4 has been transformed into pink-coloured stable gold sol having lambda(max) at 523 nm (epsilon = 3.06 x 10(3)l . mol(-1)cm(-1)) at room temperature in aqueous Triton X-100 (TX-100) upon photoirradiation. It is a very rapid and simple process and the absorbance at 523 nm is a direct measure of gold concentration. Beer's law is obeyed in the range of 0-150 ppm of gold. The relative standard deviation for 22.7 and 90.9 ppm of gold are 2.8 and 2.5% respectively. The 95% confidence limit (ten determinations) for 22.7 ppm of gold is 23.6 +/- 0.5 ppm. Sandell sensitivity is 6.44 x 10(-2) mu g cm(-2). TX-100 acts both as a reducing agent and a stabilizer here. Statistical parameters, effects of TX-100 concentration, irradiation time and interferents are studied. The method is applicable for ore and synthetic mixture analysis. (C) 1998 Elsevier Science B.V. All rights reserved.