Microwave dissolution techniques for the analysis of geological materials by ICP-MS

Microwave ovens are being used increasingly for the dissolution of wide range of geological materials. Such devices are more useful especially in conjunction with high sensitive multi-element techniques such as inductively coupled plasma mass spectrometry (ICPMS). This study evaluates the data of several trace and ultra-trace elements including specialized groups of elements such as rare earths, and platinum group elements and gold in a variety of rock and ore samples after the samples were subjected to microwave digestion followed by ICP-MS analysis. Microwave digestion yielded very clear solutions rapidly. Data with reasonable precision and accuracy were obtained even for elements such as Zr, Hf, Nb and W the quantitative recoveries of which are very difficult to obtain using conventional open acid decompositions. Near-quantitative recoveries were obtained for Pt, Pd, Ag and Au even in difficult to dissolve 'chromite ore' samples. The gold values obtained on 10 g quantities of several field samples, and few international gold reference samples demonstrated the utility of microwave dissolutions in combination with ICPMS in gold exploration studies.