A modified persimmon powder sorbent for selective separation and determination of trace gold in geological samples by ICP-MS

Abstract

A novel method that uses chemically modified persimmon powder for solid extraction of Au prior to the determination by inductively coupled plasma-mass spectrometry (ICP-MS) was investigated. Experimental conditions such as acid concentration, sample flow rate and volume, eluent conditions and interfering ions were carefully examined. Gold can be quantitatively adsorbed on the new sorbent from solution of 3% (v/v) aqua regia, and then the trace gold adsorbed on the microcolumn can be effectively eluted with a mixture of 2.0% thiourea and 0.12 mol L⁻¹ HCl. The transition- and heavy-metal ions did not interfere with either the separation/preconcentration or the determination. The maximum adsorption capacity of the sorbent was 25.3 mg g⁻¹. Under optimal conditions, the detection limit for gold was 1.32 ng L⁻¹ in the geological sample, and the relative standard deviation was 0.83% (n = 11) at 1.0 μg L⁻¹. The proposed method was validated by analyzing three certified reference materials and applied to the preconcentration and determination of trace gold in geological samples with satisfactory results.