Current Developments in the Quantitative Determination of PGE for Basic and Applied Geochemical Studies

Platinum group elements (PGE: Ru, Rh, Pd, Os, Ir, Pt) are highly siderophile and chalcophile, and their distribution within the crustal rocks is very heterogeneous and are generally present at exceedingly low concentrations (ng/g and sub-ng/g levels). As a result, their accurate determinations in terrestrial rocks are very challenging and reliable analytical techniques are required to obtain high quality data that are needed for both basic and applied studies. The past decade has witnessed several developments in the analytical instrumentation and sample preparation techniques which helped in generating high quality analytical data for PGE especially in their exploration studies. Reliable techniques were developed for the analyses of NiS and Pb beads directly by LA-ICP-MS and emission spectrometry which resulted in increased throughputs that are required for exploration studies. Hydro-geochemical investigations are useful in areas covered with thick vegetation without any outcrops, and also have the added benefit of functioning as baseline environmental data. On the micro-beam analyses front, spectacular developments have taken place particularly using laser ablation - inductively coupled plasma - mass spectrometry (LA-ICPMS). This technique provided multi-PGE analyses of PGE-bearing sulfide minerals at ng/g levels leading to better understanding of PGE geochemistry in magmatic systems. This technique can be used in combination with electron probe microanalyses (EPMA) for minor and major elements and with quantitative image analysis to provide the data necessary to understand PGE behavior. This paper evaluates the recent advances made in related areas such as bulk chemical analysis, pathfinder elements, insitu studies; hydro-geochemical prospecting methods, selective extraction methods, PGE certified reference materials and their contributions in the exploration studies as well as in related basic studies of these valuable metals.