HIGHLY SENSITIVE 14C AND 3H QUANTIFICATION OF BIOCHEMICAL SAMPLES USING ACCELERATOR MASS SPECTROMETRY

摘要

Accelerator Mass Spectrometry (AMS) is an isotope ratio mass spectrometer that quantifies low levels of rare isotopes with half-lives between 10 and 108 years. Typical sensitivities are 106 atoms in a milligram-sized sample. AMS was originally developed for use in the geosciences as a tool to carbon date archaeological artifacts, but has applications in many fields. In the biosciences, the extreme sensitivity of AMS is used to trace nutrients, toxins and therapeutics in humans and animals using less than Uglkg doses containing between 1-100 nCi of 14C [1, 2]. This sensitivity is used to reduce sample size, reduce chemical exposures to environmental or physiological levels, reduce radiation exposures to subjects, and/or reduce radioactive (and "mixed") waste. Compared to decay counting, AMS provides for a much higher measurement throughput for low activity samples. For example, a milligram-sized sample containing 1 dpm of C can be measured to 3% precision in several seconds. That same sample would require approximately 1 week of decay counting to obtain similar precision.