Arthur Holmes Trace Element and Isotope Laboratories
Over recent years isotope geochemistry has been dominated by technical developments in mass spectrometry that have enabled the study of elements that previously could not be measured to a high precision, and measurements of the very highest precision on ever smaller samples. The advent of multi-collector ICP mass spectrometry (MC-ICP-MS) has resulted in enormous progress on a number of different fronts. These instruments offer a reasonable overall transmission efficiency for all elements (1 to 2 ions for every 1000 atoms in sample) and good analytical precision (20-30 ppm relative errors) and permit rapid sample analysis. However, for many elements, the transmission efficiency of MC-ICP-MS does not approach the ionisation efficiency for thermal ionisation mass spectrometry (TIMS) (e.g. for Os 25-30 ions for every 100 atoms loaded on the filament). Thus, TIMS instruments, particularly in the field of negative thermal ionisation and for very small samples, still have a significant role to play.
In Durham we are one of the few laboratories world-wide to have embraced the best that both of these techniques has to offer and we have recently invested in new facilities for chemistry and mass spectrometry that are shared on an open access basis, both within the Department and across the University. For precise isotope measurement we have two TIMS (Thermo Fisher Triton) and two MC-ICP-MS (Thermo Fisher Neptune) instruments.
For trace element measurement we have 3 ICP-MS instruments, including fast scanning high resolution (Element 2), and low noise collision cell (Thermo XSERIES 2) instruments, with a new ICP-OES.