Alternative Sample Introduction Techniques to Nebulization of Solutions in Inductively Coupled Plasma Spectrometry
The objective of this thesis was to explore alternative sample introduction techniques for inductively coupled plasma mass spectrometry (ICPMS) and optical emission spectrometry (ICPOES). This work was conducted as part of a Collaborative Research and Development project with Activation Laboratories Ltd., Ancaster, Ontario. 1. The first approach involved the development of a sample preparation method for the direct analysis of lithium borate fused X-ray fluorescence (XRF) discs by ICPMS with a mixed-gas plasma and flow injection for the introduction of slurries into the ICP. Three dispersing agents were initially explored, however a 4% (m/m) solution of Triton-X in 2% HNO3 DDW was found to homogenously suspend the ground particulate in solution, yielding highly reproducible injection peaks. External calibration by aqueous standards did not yield consistent results to the certified values at high slurry concentrations, regardless if matrix matching of the standard was performed. Calibration by standard addition was also explored and was found to be most accurate when the slurry concentration was well diluted and that the flow rate of the carrier did not exceed 1 mL/min, as it was suspected that particle agglomeration was occurring at higher slurry concentration and higher flow rates. 2. The second approach involved electrothermal vaporization (ETV) coupled to ICPOES for the analysis of solid fire assay buttons. A nebulization/pre-evaporation system was initially explored to prevent plasma overloading due to the mass of the button, however a N2 sheath gas was selected as it provided higher plasma robustness conditions to that of the previous approach. External calibration by aqueous standards were improved upon through utilization of the internal ETV temperature program and a venting valve system for the drying of solution. Significant Ag2S deposition along the inner transfer tube prevented accurate agreement of calculated to certified values by both aqueous and solid external calibration due to the differences in transport efficiencies. The addition of an optimized H2 gas flow rate into the reaction gas aided in reducing Ag2S deposition along the transfer tube to the plasma, however non-proportional signal to mass intensities were still observed as Ag2S deposition was not eliminated.