Determination of Aluminium-26 in Biological Materials by Accelerator Mass Spectrometry

Abstract

Studies of the biological chemistry of aluminium can gain significantly from the use of the long-lived isotope ²⁶Al as a tracer, although the cost of the isotope often precludes its determination by radiochemical counting techniques. Accelerator mass spectrometry (AMS) provides an ultra-sensitive method of determination, free from isobaric interference from atomic (²⁶Mg) or molecular species. The source materials for AMS can be aluminium oxide or phosphate, both of which can be readily prepared at a sufficient level of purity from biological substrates. Natural aluminium (²⁷Al, 100%) is added to the preparations as a chemical yield monitor and to provide the reference for the isotope ratio measurement. ²⁶Al/²⁷Al ratios can be determined over the range 10^–14–10^–7, implying a limit of detection for ²⁶Al of around 10^–18 g. The precision of measurement and long-term reproducibility are <5% and <7% (RSD), respectively. Chemical methodologies for routine measurements on blood and urine samples have been developed.