The kinetics of diastereomeric amino acids witho-phthaldialdehyde

Abstract
The kinetics of the reaction of the amino acid epimers L‐isoleucine, D‐alloisoleucine, L‐threonine, and D‐allo‐threonine with o‐phthaldialdehyde and mercaptoethanol were determined at 25°C. L‐Isoleucine reacts faster than its D‐epimer whereas L‐threonine reacts slightly slower than its D‐epimer. In the case of isoleucine, the consequence can be an allo/iso ratio which in the worst case is 25% too low if these amino acids are quantified by liquid chromatography and o‐phthaldialdehyde fluorescence detection. The effect on dating of fossils by amino acid racemization is discussed.