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

Prior to conducting analyses of all samples by HPLC, the D- and L-amino acids of three samples were determined by both HPLC and ion exchange column chromatography (IEC). the results are in Table 7, and the D/L ratios determined by the two methods were in excellent agreement. Table 7 D/L ratios for various amino acids determined by ion exchange column chromatography (IEC) and by high performance liquid chromatography (HPLC) Number and age of samples (year) Analytical method The D/L ratios for various amino acids Number and age of samples (year) Analytical method Phe Asp Ala He Val 1.15600 IEC HPLC 0.568 0.553 0.367 0.389 0.153 0.163 2.38450 IEC HPLC 0.395 0.401 0.123 0.121 3.46900 IEC HPLC 0.487 0.492 0.146 0.149 2.3. Results and discussion The analyses data on 24 fossil bone samples from various Hungarian museums of known age are summarised in Table 8. Six amino acids (His^ histidine, Phe= phenylalanine, Asp= aspartic acid, Ala= alanine, Ile= isoleucine, Val= valine) are presented. These may be considered as being the most suitable for age determination because some of them show very fast racemization (His, Phe, Asp), while others show very slow racemization (Ile, Val). Analytical data for other analysed amino acids are not presented in Table 8 in order to make it more synoptic. None of the ratios lower than 0.1 or higher than 0.7 are presented in Table 8 because, in these cases, the accuracy of age determination was doubtful. Calibration curves of phenylalanine, aspartic acid, alanine and isoleucine plotted on the basis of the data in Table 8 can be seen in Figures 1, 2, 3 and 4, respectively. Half lives of AAR were also calculated from the data of Table 8 and are presented in Table 9. From the data of Table 8, His, Phe, Asp and Ala contents can be used for the age determination of samples which are 2-12 000, 3-20 000, 5-35 000 and 10-80 000 years old, respectively. Age of samples older than 30 000 and 50 000 years can be determined on the basis of He and Val content, respectively. Data in Table 8 were corrected (reduced) with the D-amino acid content of a fresh pig bone to eliminate the errors of analysis. When fresh pig bone was hydrolysed with 6M hydrochloric acid for 24 h at 110 °C, the forms of glutamic and aspartic acids, respectively, represented 1.9 and 1.3% of the totals due to racemization during processing. Concentrations of the D-form for the other amino acids were negligible. However, all analyses were corrected for the small concentrations present in fresh pig bone. 32