Aluminum-26 as a biological tracer using accelerator mass spectrometry

The development of accelerator mass spectrometry (AMS) has provided a practical method of detection for the only isotope of aluminum suitable as a tracer, $\sp{26}$Al. The use of $\sp{26}$Al as a tracer for aluminum has made possible the study of aluminum metabolism and the pharmacokinetics of aluminum-containing drugs at physiological levels. An overview of the various advantages of using $\sp{26}$Al as a tracer for aluminum and a general description of the AMS technique as applied to bio-medical applications is given. To illustrate the versatility of $\sp{26}$Al as a tracer for aluminum, $\sp{26}$Al studies of the past several years are discussed briefly. In addition, Two novel investigations dealing with $\sp{26}$Al-labeled drugs will be presented in more detail. In one of these studies, it was found that $\sp{26}$Al from aluminum hydroxide and aluminum phosphate vaccine adjuvants appeared in the blood just one hour after intramuscular injection. This is a surprising result since the currently held theory of how adjuvants work assumes that adjuvants remain insoluble and hold the antigen at the injection site for a long period of time. In another project, $\sp{26}$Al-labeled antiperspirants are being characterized by combining AMS with traditional analytical and chromatographic techniques. Future directions for this and other possible studies are discussed.