Determination of mercury in gold bullion by flame and graphite furnace atomic absorption spectrometry

A procedure was developed to determine mercury in unrefined gold by flame and graphite furnace atomic absorption spectrometry (FAAS and GFAAS). High acid content (60-80% of concentrated HCl in water) was needed to keep silver (usually present with gold deposits) in solution as a chloro-complex. Although Hg determinations by FAAS and GFAAS have poor sensitivity, the relatively high concentrations of Hg (0.02-0.2%) are well within the capabilities of these techniques. No significant difference was observed between concentration values obtained from these techniques and those obtained by inductively coupled plasma atomic emission spectrometry (ICP-AES) with the same sample. The limit of detection (3 s) was found to be approximately 20 mu g g(-1) for both GFAAS and FAAS determinations. However, FAAS is the recommended method due to simplicity of operation, higher sample throughput, low cost, and ease of method transfer to other laboratories. (C) 1998 Published by Elsevier Science B.V. All rights reserved.