Determination of Trace Gold in Geochemical Exploration Samples by Z-2000 Polarized Zeeman Graphite Furnace Atomic Absorption Spectrophotometry

A method for the determination of trace gold in geochemical exploration samples by Z2000 polarized Zeeman graphite furnace atomic absorption spectrophotometer (GFAAS) was reported in this paper. The sample was dissolved with 50% aqua regia and the gold in the sample solution was then concentrated with polyurethane foam plastic and using 10 g/L thiourea solution as release agent. The factors influencing Au adsorbption, such as physical properties of polyurethane foam plastic and concentration of aqua regia were studied. And GFAAS determination parameters including temperature and time in ashing, atomization and cleaning steps, carrier gas flow rate, lamp current intensity were also optimized. The detection limit of the method is 0.3 ng/g for gold and the recovery is 95.0％～101.0％ with precision of less than 8.0%RSD (n＝12). The method has been applied to the determination of trace Au in National Standard Reference Materials (GBW 07243~GBW 07245) and the results were in agreement with certified values.