Electron Spin Resonance Dating IndexGeological Dating Amino acids are the building blocks or sub-units of proteins and proteins are the richest organic molecules found in cells. Since they are related to whole aspects of cell structure and function, they are found in every part of every cell. Protein generally consists of 20 varying amino acids . Most amino acids in the proteins have at least one asymmetric carbon atom and that can exist in two ways. Those two have mirror-images of each other, just like left and right hands.
Amino acids complete the racemization process when the amounts of L and D amino acids are equal.
The older the sample material is, the greater the extent of racemization would be. This means the organism that has died a long time ago might have more D-amino acids than the ones that died recently. In this way, the extent of racemization process can serve as a dating technique. The ratio of L and D amino acids can be measured by gas and liquid chromatography. Racemization can date samples to approximately 5,000 - 100,000 years old.