Reduction of the matrix effects in the gold and silver analysis using the ICP-MS technique

Inductively coupled plasma mass spectrometry (ICP-MS) has been an indispensable technique in the analysis of geological samples in the last few decades. This technique can determine a large number of trace elements, such as the precious metals and rare earth elements. However, the technique is limited by the spectral and non-spectral interferences, which can affect the results of analysis. The aim of this study was to reduce the non-spectral interferences by the method of sample dilution (1000 - 10000). A sample containing gold-bearing minerals was subjected to a digestion in aqua regia, and determination was performed on a NexION 1000 PerkinElmer ICP-MS instrument. The results showed that the differences in gold and silver concentrations in the standard and He modes were insignificant at a dilution of 10000 indicating that the matrix effect was reduced applying a higher dilution. The results of XRD analysis have showed that the sulphide minerals pyrite (FeS2 ) and covellite (CuS) were very abundant in the tested samples, so the digestion of these samples with aqua regia has yielded the solutions containing iron and copper as the most abundant components of the matrix.