A novel rapid detection approach for the analysis of radionuclides in environmental samples using graphite MALDI mass spectrometry

Initial studies into the analysis of Uranium and Lanthanide salts by graphite matrix assisted laser desorption ionisation–time of flight–mass spectrometry (GALDI–ToF–MS) are presented. It is shown that GALDI–ToF–MS represents a more effective method for ion generation compared to that observed by direct laser irradiation, providing more sensitive analysis and enhanced mass spectral quality. Assessment of sensitivity, detection limits and isotope signature determination is given with absolute detection limits having been found to be in the low ng to pg range and abundance measurements being consistent with expected values to within 2–10 % depending on the relative isotope ion intensities. Using imaging software, GALDI–ToF–MS can be used to identify the presence of low micron-sized uranium oxide particles and establish their distribution across a substrate surface to enable particle location and in so doing identify particles of interest which are of non-natural, enriched content. In this context, GALDI–ToF–MS is proposed as a novel screening method for uranium containing micro-particles which has potential as a rapid and low cost means for particle location to enable effective sampling using micro-manipulation and optical microscopy, for onward isotope ratio mass spectrometry.