The use of direct current argon plasma spectroscopy for quantitative analysis of geological samples

The focus of this project was the development of a process of analyzing geological samples which contain moderate amounts of silica. The main emphasis was put upon the reduction of the amount of "wet" chemistry and laboratory time involved in such analysis. Previous elemental analysis of such samples relied upon time consuming techniques such as combustion and precipitation reactions. Moreover, these analyses required the use of highly corrosive hydrofluoric acid (HF). This project utilized a DC Argon Plasma Spectrometer (DCP) for all elemental analyses. Furthermore, the only chemical required for the project was concentrated nitric acid. This project proposed that treatment of the samples with hot concentrated nitric acid would serve to digest the samples sufficiently to extract all the ions for analysis by the DCP. In summary, analyzed samples from the Thorne Smith company were digested in hot concentrated nitric acid. The silica residue was filtered out and the samples made up to volume. They were then introduced to the DCP for analysis for Calcium, Magnesium, Iron and Aluminum. These values were converted to the oxide concentrations and compared to the literature data. After two procedures failed to correlate with the classical results a third technique was developed which proved to be fairly accurate and very precise. This final technique involved three nitric acid treatments. It is felt that upon follow up work on this project the results of this method will correlate well with the literature data.