Preparation of gold-coated sand for ultra-trace mercury analysis

Abstract

In this study, the gold-coated sand was prepared to make gold-trap for mercury analysis at ultra-trace levels. The preparation process was conducted with the etching of sand surface to form silanol groups using a mixture of H₂O₂/H₂SO₄ followed by the replacement of the silanol groups by amino groups with aminopropyltriethylsilane. The amino-modified surface is embedded with Au atoms by soaking the amino modified sand in nano gold solution then the Au film is thickened with a mixture of Au(III)+NH₂OH.HCl. The gold-coated sand can capture up to 21 μg Hg per 1 g of sorbent. The interferences for the efficiency of mercury sorption such as HNO₃, HCl, H₂SO_4­ and temperatureare were investigated. The gold-coated sand was successfully applied for mercury analysis in certified reference materials (DORM-4) by CV-AAS and combustion/thermal decompostion methods.