Utility of solid phase extraction for spectrophotometric determination of gold in water, jewel and ore samples

A highly sensitive, selective and rapid method for the determination mu g L-1 level of Au(III) based on the rapid reaction of Au(III) with 2,3-dichloro-6-(3-carboxy-2-hydroxY-1-naPhthYlazo)quinoxaline (DCHNAQ) and the solid phase extraction of the colored complex with a reversed phase polymer-based C18 cartridge have been developed. The DCHNAQreacted with Au(III) to form a violet complex of a molar ratio 3:1 [DCHNAQ to Au(III)] in the presence of 5.0 M of phosphoric acid solution and Triton X-100 medium. This complex was enriched by the solid phase extraction with a polymer-based C18 cartridge. The enrichment factor of 100 was achieved. The molar absorptivity of the complex is 2.73 x 10(5) l mol(-1) cm(-1) at 633 nm in the measured solution. The system obeys Beer's law in the range of 0.02-1.30 mu g ml(-1), whereas the optimum concentration ranges obtained from Ringbom plot was 0.08-1.24 mu g ml(-1). The relative standard deviation for ten replicates sample of 0.6 mu g ml(-1) level is 1.28%. The detection and quantification limits, are 6.1 and 19.5 ng ml(-1) in the original sample. This method was applied to the determination of gold in water, jewel and ore samples with good results comparing to the GFAAS method. (c) 2010 Elsevier B.V. All rights reserved.