Racemization dating definition
k where d L/dt is negative since the L-isomer experiences only a net decrease over time until d L/dt becomes zero at equilibrium.The integral solution of Equation (1) is (Bada and Schroeder 1972, Petit 1974) D, together with the accepted value of 1.25 for D/L at equilibrium.AMINO ACID SURVIVAL IN PHANEROZOIC FOSSILS Since amino acids have widely varying degrees of stability, after the death of an organism the less stable amino acid components will decompose more rapidly than those which are more stable, producing an amino acid signature that is increasingly distributed toward the more stable components as time progresses (Hare and Abelson 1967, Lee et al. Because of the range of variation among individual members of the same species (Hare and Abelson 1965, Hare and Mitterer 1967, King and Hare 1972, Jope 1980), amino acids may be expected to provide at best only a broad indication of fossil age.Uncertainty as to the extent to which modern organisms represent in detail the characteristics of their ancient counterparts introduces additional lack of precision in a fossil age based on amino acid ratios.
The laboratory procedure involves only the measurement of two components that can be determined by standard chromatograph techniques with relatively inexpensive equipment.
The instability of the twenty amino acids which are the building blocks of proteins provides a possible means for determining the ages of fossils.
A preliminary recognition of this possibility appeared in the scientific literature 30 years ago (Abelson 1955).
At the present time there is insufficient knowledge concerning the effective average racemization rate in a fossil as a function of time to justify dependence on D/L ratios for a quantitative determination of age.
The survival of amino acids in fossils from the Paleozoic era and the trend for the apparent racemization rate constant to decrease with conventional fossil age assignment raise a serious question concerning the accuracy with which radioisotope age data have been used to represent the real-time history of fossils.