Development of novel calibration strategies for laser ablation inductively coupled plasma mass spectrometry

摘要

Calibration has been termed the "Achilles heel" of Laser Ablation Inductively Coupled Plasma Mass Spectrometry (LA-ICP-MS). This is down to the fact that Certified Reference Materials (CRMs) do not exist for the majority of sample types and the detrimental effects of elemental fractionation and the matrix dependency of the ablation process. This thesis investigates the potential for two calibration strategies: one based upon the online additions' of aqueous calibration standards; the other, upon the pressing of powders into discs utilising organic chromophores that absorb at the lasing wavelength of 213 nm. Finally, deviations of the above strategies have been devised enabling the absolute quantitation technique of isotope dilution to be employed. All the strategies investigated have been validated by analysis of a wide range of CRMs including: glasses, plastics, metals, soils, sediments and powdered plant matter. Throughout this project, useful insights into fundamental ICP and ablation processes have been obtained. The online additions strategy allowed investigation into mass . loading induced matrix effects, and the relative merits of utilising a wet plasma rather than a dry; whilst the pressed powder approach allowed examination of fundamental, absorption related ablation processes.