Automated rock analysis for forty elements

Abstract

The "Centre de Recherches Pétrographiques et Géochimiques" has been involved in optical emission spectrochemical rock analysis for more than three decades. An enormous bottleneck in rock analysis laboratories is the preparation of samples. Automation of different steps involved in sample preparation schemes has been a constant subject of development in our production-oriented laboratory. This effort has been eased by the fact that all sample preparation schemes for the past three decades have been based on an initial lithium borate fusion with switch-over from solid analysis by arc/spark excitation to solution analysis in 1974 with the arrival of plasma excitation sources (microwave plasma, inductively coupled plasma). At present, a single solution prepared after an initial lithium borate fusion is used for the determination of over forty major, minor, and trace elements. All steps in the preparation scheme (weighings, fusion, acid dissolution, dilution, and preconcentration with ion-exchange columns for rare-earth elements, Sn, W, and Mo as well as for U and Th) have been either automated or robotized. Because of automation at all levels of analysis including that of running sample solutions with the spectrometer, high production of accurate rock analysis for forty elements has become routine at low cost.