Determination of aluminium-26 in biological materials by accelerator mass spectrometry

Studies of the biological chemistry of aluminium can gain significantly from the use of the long-lived isotope Al-26 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 (Mg-26) 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 (Al-27, 100%) is added to the preparations as a chemical yield monitor and to provide the reference for the isotope ratio measurement, Al-26/Al-27 ratios can be determined over the range 10(-14)-10(-7), implying a limit of detection for Al-26 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.