For measurement of carbon isotopes
The CAIS operates a 500 kV compact AMS unit for precise analyses
of carbon isotopes C-12, C-13, and C-14 at extremely low (parts
per quadrillion) concentration levels.
The National Electrostatics Corporation Model 1.5SDH-1 Pelletron Accelerator Mass Spectrometer, installed in January 2001, provides the means to directly count the number of C-14 atoms in a sample, so that even extremely small (microgram size) samples can be used for quantitative determinations of very low-level isotopic concentrations.
Precision of C-14 measurements is better than 0.3%. The sensitivity of the instrument is comparable to that of much larger units, with theoretical detection limits as low as 4 attomoles (4 x 10-18 moles) of C-14. Geological graphite 14C/12C ratios average 7.5 x 10-16.
The CAIS presently offers a sample preparation service, which involves the conversion of carbonaceous materials to graphite and submission for AMS analysis. Samples sent for AMS preparation must contain at least 2 mg of carbon by weight.
For a less expensive analysis, samples may also be submitted pre-prepared to CO2 or graphite form.