Determination of trace Au in geochemical exploration samples by GFAAS

The geochemical exploration sample was roasted and dissolved with aqua regia. The trace gold is absorbed by polyurethane foam from aqua regia medium under the presence of Fe³⁺ and released in 10 g/L thiourea solution. The trace gold is determined by GFAAS with the slope warming. The detection limit of the method is 0.1ng/g with the precision (RSD, n=12) of 4.2 %~10.8 %. The results conform to the certified values through the national standard reference material tests.