M. Járó - L. Költő szerk.: Archaeometrical research in Hungary (Budapest, 1988)
Dating - CSAPÓ János, KÖLTŐ László , PAP Ildikó: Archaeological age determination based on the racemization and epimerization of amino acids
the fact that the racemization occurring during the hydrolysis has to be taken into account when determining the age; the D- and L-amino acid ratios have tobe corrected by this figure. A further source of error in acidic hydrolysis may be that asparagine and glutamine are transformed into aspartic acid and glutamic acid during the process of hydrolysis. There is no unanimous opinion on whether the fossils contain the two acid amids, nor is there agreement on their desamination time and the error they can cause in the determination of the ages of the liquids. 3. The process of racemization of amino acids In general the racemization of amino acids can be described as follows : L-amino acid — D- amino acid where kj and k 2 represent the reactional speed constants of the formation and reformation, from which the equilibrum constant is K = k t /k 2 . The reaction speed can be described by the following general formula: d[L] = k t [L]-k 2 [D], dt where [L] and [D] are the L- and D-enantiomer concentrations. By performing the integration we get: Inf "WM V(l.K-)k,t.C, ehere K' = 1 /K = k 2 fki . The integration constant - if where is no D-enantiomer present is equal to 0, otherwise C = ta 1 + [DQ]/[LQ] [D 0 ]/[L 0 ] Bada and Protsch (1973) calculated for the D/L- aspartic acid ratio for present cow bones a value of 0.07 which was the racemization during the hydrolysis and the processing. From this the calculated value for C at t = 0 is 0.14. For free amino acids in water solution the speed of formation and reformation is equal, therefore kj = k 2 , and the reaction equation can be simplified as follows: Ji*EU k ,.c. \ 1-[D]/[L] / The characteristic and easy to use parameter of racemization is the half-time. By definition this is the time that 25% D-enantiomer and 75% L-enantiomer are present in
