Study Workflow

AMS-Based Study Workflow

AMS-Based Clinical Studies

A typical AMS study requires administration of 100 nanoCuries or less of radiotracer to the study subject. This radiological exposure is equivalent to an effective exposure received in a two hour intercontinental plane flight. In addition to significantly reduced radiological exposure, AMS-based studies can be performed with sub-pharmacologic doses of new compounds without any trade-offs on detection.

Sample Preparation

Biological samples such as plasma, urine, fecal and tissue homogenates are first combusted to CO₂. If structure information is needed, the sample is first separated into individual fractions by HPLC before combustion to CO₂. The CO₂ gas is then reduced to fullerene over an iron catalyst to obtain solid graphite.

AMS Measurement

Graphite samples are placed onto an AMS instrument where a beam of C^- ions is produced by bombarding the cool cesiated surface of the graphite sample with about 5 keV Cs⁺ ions. The C- beam produced by the sputtering of the sample by the Cs+ beam is accelerated, focused and mass analyzed into mass 14, and 13 amu beams. By recording the ¹³C current and ¹⁴C counts as known and unknown samples are sputtered, the amount of ¹⁴C present in a biological sample is determined to high accuracy. Importantly, nitrogen (also 14 amu) does not make a negative ion and is effectively removed as a confounding atomic isobar.