Improving the accuracy and precision of laser ablation inductively coupled plasma spectrometry analysis of heterogeneous materials

Laser ablation inductively coupled plasma mass spectrometry (LA-ICPMS) has developed into an important and indispensable tool for solid sampling analysis. The use of LA-ICPMS allows rapid in situ analysis requiring minimal sample preparation while using a minimal amount (micrograms) of sample. Low detection limits of parts per billion are also easily achieved for most elements using the LA-ICPMS. However, the use of LA-ICPMS has yet to be fully developed as a rapid and routine method of analysis for heterogeneous materials. Matrix-matched standards are required for quantitative analyses. Variations in the laser ablation process, and elemental and isotopic fractionations may occur during analysis affecting both precision and accuracy.; The goal of this research is to improve the precision and accuracy of LA-ICPMS analysis of heterogeneous materials.; Initial stages of the study involved fundamental studies to determine the causes of poor precision and accuracy in LA-ICPMS. Results showed that the limiting source of noise in LA-ICPMS is flicker or excess low frequency noise originating from variations in the sample aerosol as they are created, transported and introduced into the ICP. Particle size distribution studies of laser-ablated material were then performed to determine the ablation parameters that produced sample aerosol with the optimum particle size distribution yielding the best ICP signal in terms of signal intensity and stability.; An inertial impactor was used to improve the particle size distribution of the ablated material prior to its introduction into the ICPMS. Results showed that removing the larger particles from ablated material improved ICPMS signal precision. ICP-induced elemental and isotopic fractionation effects were also reduced by removing larger particles from the ablated material. Light scattered by ablated material was also collected and used for normalization of the ICPMS signal. Results show that normalization to light scattered by the ablated material compensated for variations in the mass ablated, or the number of particles ablated during an analysis. The use of the spectral emission intensity of an analyte collected from the laser-induced plasma to normalize its corresponding LA-ICPMS signal was also investigated.; Finally, the proposed approaches to improving the precision and accuracy of LA-ICPMS were applied to heterogeneous nuclear waste simulants.