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 2 D-amino acid content of bovine ribonuclease hydrolysed by 6 M hydrochloric acid at 170 °C for different times Amino acid 6 M HCl, 110°C for 24 h 6 M HCl, 170°C for Amino acid 6 M HCl, 110°C for 24 h 15 min 30min 45min 60min Asp 6.73 2.23 3.02 3.62 3.89 Glu 4.58 1.97 2.74 2.93 3.28 Thr 3.64 1.99 2.16 2.54 2.84 Ala 2.95 1.69 1.99 2.22 2.54 Val 2.34 1.61 1.90 2.03 2.17 Phe 3.28 2.30 2.83 3.01 3.10 His 1.96 1.22 1.59 1.63 1.81 Data expressed as in Table 1. Table 3 D-amino acid content of bovine ribonuclease hydrolysed by 6 M hydrochloric acid at 180 °C for different times Amino acid 6 M HCl 110°Cfor 24 h 6 M HCl, 180 °C for Amino acid 6 M HCl 110°Cfor 24 h 15min 30_min 45min Asp 6.73 2.69 4.28 6.19 Glu 4.58 2.94 3.42 4.61 Thr 3.64 2.45 3.06 3.39 Ala 2.95 2.37 2.89 3.31 Val 2.34 1.99 2.43 2.70 Phe 3.28 2.97 3.12 3.78 His 1.96 1.77 2.09 2.53 Data expressed as in Table 1. Data in Tables 1, 2, and 3 were subjected to analysis of variance with temperatures, times and amino acids representing main effects. All main effects plus interactions of temperature-time and temperature-amino acids were highly significant (P<0.001) sources of variance affecting degree of racemization. Increases of temperature and time of hydrolysis caused increases in racemization. The degree of racemization, when averaged over all time-temperature treatments, varied from 1.16% for His to 2.52% for Asp. Degree of racemization values (average for all amino acids and for Asp) were fitted to a curvelinear and interactive function of time and temperature. The model explained 94to 96% of the variation in the dependent variable. The function for Asp indicated that 3.6% racemization would occur at 60, 42 and 28 minutes, respectively, for 160, 170 and 180 'C temperatures. Corresponding times for average racemization were 70, 35 and 20 minutes to produce 2.33% racemization. 27