Amino racemization dating
According to Bada, aspartic acid was used because it has the fastest racemization rate. Unfortunately, none of the proteins amino acids racemize as fast and thus, there is, in general, no detectable amounts of racemization other than for aspartic acid, he explains.Racemization is the process in which one enantiomer of a compound, such as an L-amino acid, converts to the other enantiomer.
With these measurements, scientists can estimate the rate at which one enantiomer is converted to the other.
The levels of D- and L-aspartic acid were analyzed by ion exchange chromatography or reversed-phase HPLC.
The relative proportions of each enantiomer were measured using fluorescence detection.
According to their findings, no evidence of DNA could be found in samples in which the D/L ratio was higher than 0.08.
Consequently, all samples with D/L ratios equal to or below 0.08 produced DNA sequences.