When an organism dies, control over the configuration of the amino acids ceases, and the ratio of D to L moves from a value near 0 towards an equilibrium value near 1, a process called racemization.
These effects restrict amino acid chronologies to materials with known environmental histories and/or relative intercomparisons with other dating methods.
Temperature and humidity histories of microenvironments are being produced at ever increasing rates as technologies advance and technologists accumulate data.
This includes racemization rate variation among species and organs, and is affected by the depth of decomposition, porosity, and catalytic effects of local metals and minerals.
[8][9][10] In recent years there have been successful efforts to examine intra-crystalline amino acids separately as they have been shown to improve results in some cases.
Paleopathology and dietary selection, paleozoogeography and indigeneity, taxonomy and taphonomy, and DNA viability studies abound.
Amino acid racemization also has a role in tissue and protein degradation studies, particularly useful in developing museum preservation methods.
Alternatively, the particular amino acid can be separated by chromatography or electrophoresis, combined with a metal cation, and the D:L ratio determined by mass spectrometry.