These two radiocarbon dating methods use modern standards such as oxalic acid and other reference materials.Although both radiocarbon dating methods produce high-quality results, they are fundamentally different in principle.After pretreatment, samples for radiocarbon dating are prepared for use in an accelerator mass spectrometer by converting them into a solid graphite form.This is done by conversion to carbon dioxide with subsequent graphitization in the presence of a metal catalyst.An accelerator mass spectrometer has a run time of a few hours per sample.Lastly, it must be noted that AMS measurements usually achieve higher precision and lower backgrounds than radiometric dating methods.At this stage, molecules that may be present are eliminated because they cannot exist in this triple charged state.
The greatest advantage that AMS radiocarbon dating has over radiometric methods is small sample size.
Mass spectrometers detect atoms of specific elements according to their atomic weights.
They, however, do not have the sensitivity to distinguish atomic isobars (atoms of different elements that have the same atomic weight, such as in the case of carbon 14 and nitrogen 14—the most common isotope of nitrogen).
Reference materials are also pressed on metal discs.
These metal discs are then mounted on a target wheel so they can be analyzed in sequence.