Determination of Gold and Silver in Twenty Plants from the Copper Mining Area by Inductively Coupled Plasma-Mass Spectrometry

The preconcentration and determination of gold and silver in twenty plants from the copper mining area by ICP-MS was described. The plant samples were decomposed by dry-ashing and aqua regia. Ag-107, Ag-109 and Au-197 were chosen as determining isotopes and Rh-103 and Tl-203 were chosen as internal standards. The conditions of sample digestion were elected and the interferences on instrument measurement were eliminated through the experiments. The detection limits of method were 0.048 and 1.06 ng.g(-1) for Au and Ag. The precisions(n=5) were between 0.85% and 9.05% RSD, and the recoveries were between93.6%similar to 101.6%(Au, Ag). The method is sensitive quick, simple and has been applied to the analysis of gold and silver in plants from the copper mining area. Under the given analytical conditions, the results showed that the contents of the Au and Ag varied in these diferent plants, the ranging between 0.181 similar to 0.99 ng.g(-1) for Au and 280 similar to 2 150 ng.g(-1) for Ag respectively. The geochemical anomalies on Ag were discovered in Pteris,Dicranopteris pedata and Bolbitis heteroclita, which can be regarded as prospecting effective indicator plants.