Biomolecular tracing using long-lived isotopes

Accelerator mass spectrometry (AMS) was developed over the past 15 years as an essential tool for detecting long-lived, cosmogenic radio-isotopes in the earth and space sciences. We apply this technology to the measurement of chemical kinetics, primarily in biomedical systems, which had heretofore employed short-lived isotopes and/or long counting times to quantify radio-isotopic labels. AMS provides detection efficiencies of ∼ 1%, 103 to 106 better than decay-counting. Long-lived isotopes are used and detected with AMS at concentrations which reduce sample size, chemical dose, radiation safety hazards and radiolysis. We measure 3H, 7,1OBe, 14C, 26Al, 36CI, 41Ca and 129I, but most of our current program uses 14C. Initial experiments involved research on the genotoxicity of mutagens in cooked foods and reversible binding of compounds to antibodies. Through collaborations, we apply AMS detection to research in carcinogenesis, pharmacokinetics of toxins, elemental metabolism, distribution of topical medications and nutrition