Determination of uranium and thorium in aluminium with flow injection and laser ablation inductively coupled plasma mass spectrometry

Abstract

In order to determine uranium and thorium at the sub-ng g^–1 level in aluminium, the limit of detection (LOD) for continuous-flow nebulization inductively coupled plasma mass spectrometry (ICP-MS) is not sufficient, when a sample solution with the usual maximum concentration of 1 mg ml^–1 is used. Therefore, two alternative sample introduction techniques have been used, flow injection (FI) and laser ablation (LA). With FI-ICP-MS the achievement of sub-ng g^–1 detection limits is hampered by the presence of ‘spikes’. Although these spikes are also present with LA, it is possible to obtain a 0.2 ng g^–1 LOD for uranium and thorium. This LOD is achieved artificially, by rejecting all measurements containing spikes.