Determination of trace impurities in high purity gold by inductively coupled plasma mass spectrometry with prior matrix removal by electrodeposition

A novel method for the determination of 11 trace impurities (Be, Mg, Cr, Mn , Ni, Cu, Zn, Ag, Pd, Sn and Pb) in high purity gold with a combination of electrochemical deposition separation and inductively coupled plasma mass s pectrometric measurement was investigated. In the present study, an efficie nt separation procedure was developed to remove the gold matrix by the elec trodepositon method on the basis of the difference in reduction potential o f gold and the other trace impurities. The effects of deposition potential, deposition time and composition of the electrolyte on the separation effic iency were studied. According to our experimental results, most impurities, except for silver, can remain in the electrolyte and the interference from gold can be completely removed through the application of electrodepositio n at suitable potential. To achieve simultaneous separation of silver from the gold matrix, a unique complexation reaction between silver ions and amm onia ions was successfully employed to alter the reduction potential of sil ver ion. By way of a suitable adjustment of the deposition potential and th e composition of electrolytes, the spike recoveries of 11 interesting impur ities were found to be in the range of 85-105%. The limit of detection (bas ed on the 3-sigma criterion) of these elements was 10(-1)-10(-2) mu g g(-1) . The applicability of the proposed method has also been validated by the a nalysis of high purity gold reference materials (FAU9 and FAU11, Royal Cana dian Mint). Comparing with the certified values, the recoveries of interest ing elements were found to be in the range of 82-118% through the use of pr oposed method. (C) 2000 Elsevier Science B.V. All rights reserved.