Chemical Vapor Generation-ICP-AES Determination of Au in Geological Samples

Geological sample was digested with mixed acid of HCl-HNO3 (3+1), and separated and enriched with activated carbon. Au in the solution obtained was reduced with 12 g·L-1 NaBH4 solution (dissolved in 0.5 g·L-1 NaOH solution) at 90 ℃, and determined by chemical vapor generation-ICP-AES. Linear relationship between values of emission intensity and mass concentration of Au was kept in the range within 1 500 μg·L-1, with detection limit (3s) of 0.59 μg·L-1. The proposed method was used in the determination of Au in 2 standard samples (GBW 07289 and GBW 07291), and the results obtained were in conformity with the certified values.