Achaeometrical Research in Hungary II., 1988

PROSPECTING and DATING - János CSAPÓ - Zsuzsanna CSAPÓ-KISS - János CSAPÓ JR.: How the amino acids and amino acid racemization can be used and with what limits for age determination of fossil materials in archaeometry

Table 8 D/L ratios for various amino acids concerning ages of fossil samples determined by the radiocarbon method Age of samples determined by the l4

C corrected method (year) The D/L ratios for various amino acids Age of samples determined by the l4

C corrected method (year) His Phe Asp Ala He Val 2200 0.138 2800 0.162 0.101 3110 0.181 0.109 3240 0.199 0.128 4630 0.253 0.179 0.109 5460 0.312 0.225 0.128 6850 0.419 0.252 0.171 11200 0.618 0.442 0.271 0.112 12400 0.682 0.473 0.289 0.131 15600 0.561 0.378 0.158 18600 0.654 0.432 0.192 20200 0.689 0.491 0.209 22600 0.543 0.228 25400 0.580 0.246 28600 0.621 0.289 30400 0.643 0.321 32500 0.702 0.343 0.099 36900 0.381 0.118 44600 0.465 0.134 46800 0.483 0.142 54300 0.510 0.169 0.100 62200 0.586 0.188 0.115 65000 0.613 0.199 0.119 72400 0.652 0.221 0.136 Studying the calibration curves, it can be concluded that, in the case of D/L ratio being lower than 0.1, the D-amino acid content is too low and age determination is uncertain. Both curves may be considered to be linear in the D/L range of 0.1 - 0.5. It is obvious that the calibration curves can be used for age determination most satisfactorily in the linear range, (D/L between 0.1 and 0.5 where D-amino acids are present in well detectable amounts). The optimum D/L ratio can be found for each sample by analysing the amino acids best suited for age determination. E.g., for fossil bone samples of 11200 years the D/L ratio for His, Phe, Asp and Ala is 0.682, 0.473, 0.271 and 0.112, respectively. In this case the D/L ratios of Phe and Asp are recommended for determining the age of samples, however the D/L ratios of His and Ala can be used to confirm the estimate based on the ratios of Phe and Asp. 33