Solvent extraction clean-up for pre-treatment in amino acid analysis by gas chromatography. Application to age estimation from the D/L ratio of aspartic acid in human dentine.
Solvent extraction, a clean-up method for samples for the determination of amino acids by gas chromatography, was investigated and compared with a conventional ion-exchange purification. Amino acids were esterified with isopropanol and extracted with various organic solvents. The solubilities of the amino acid isopropyl esters increased with increasing solvent polarity and the size of the amino acids. The optimum pH was found to be 10.5. The method was applied to the estimation of ages by measurement of the D/L ratio of aspartic acid in human dentine. The D/L ratios so determined were slightly lower than from the ion-exchange method with respect to all dentines examined. However, there were little or no significant differences in the ages estimated by both methods, and the correlation coefficient of this method was 0.982. The method is suitable for the enantiomeric analysis of amino acids, and has several advantages in the technique and time.
Abe
I
I
College of Engineering, University of Osaka, Japan.
Tsujioka
H
H
Wasa
T
T
D000328:Adult; D000375:Aging / Q000378:metabolism*; D000596:Amino Acids / Q000032:analysis*; D001224:Aspartic Acid / Q000032:analysis*; D002849:Chromatography, Gas; D002852:Chromatography, Ion Exchange; D003804:Dentin / Q000032:analysis*; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007202:Indicators and Reagents; D008875:Middle Aged; D012997:Solvents; D013237:Stereoisomerism
D000596:Amino Acids; D007202:Indicators and Reagents; D012997:Solvents; D001224:Aspartic Acid