Determination of gold in ore samples by energy dispersive X-ray fluorescence after separation and preconcentration on polyurethane foam

A sensitive and selective method to determine gold in ore samples was developed. It was based upon gold extraction from hydrochloric acid medium by unloaded polyether type polyurethane foam (PUF). After that direct measurement on the solid sorbent by energy dispersive X-ray fluorescence (EDXRF) was done. The main parameters that control the gold sorption on PUF were evaluated. HCl concentration, sorption kinetic, amount of PUF and influence of foreign ions are some examples of these parameters. No variation in the gold system sorption was observed in the concentration range of 10 − 2 to 1 mol L − 1 of HCl. A 0.3 mol L − 1 HCl concentration was selected. The sorption kinetics of Au (III) is rapid with a half-life of adsorption (t1/2) of 0.83 min. The curve fitted by EDXRF measurement of gold Lα intensity signal on PUF was linear in the mass range of 0 to 25 μg. The calibration sensitivity was 0.0860 CPS μg − 1. The detection and quantification limits of gold in ore samples were 1.36 and 4.53 μg .g − 1, respectively. It was observed that Al, Cu (II), Fe (III), Mn (II) and Ni have no significant effect on gold sorption. The method was successfully applied to determine gold in ore reference materials. The results are in good agreement with the certified gold values at a 95% confidence level. The average relative standard deviation (RSD) was 6%.