title: Age estimation from aspartic acid racemization of root dentin by internal standard method.
abstract: In this study, we investigated the application of the internal standard method to determine age from aspartic acid (Asp) racemization. D-Methionine (D-Met) and D-norleucine (D-Nleu) were tested as internal standards for the purpose of validating the derivatization and gas chromatographic measurements. Using a set of standard amino acids plus the internal standards in constant volume, calibration plots with reasonable linearity (R > 0.98) were constructed. Based on the analysis of sample chromatograms, D-Met appeared to meet the criteria for internal standards, hence it was selected for use in D- and L-Asp quantification. The correlation between dentin age and D-/L-Asp ratios from the peak areas as well as from the absolute concentrations was investigated. Correlation coefficients were calculated as 0.98 and 0.90, respectively. The slight decrease in accuracy was attributed to the conversion of D-Asp/D-Met ratios to concentrations employing the calibration curves figured from pure Asp. Because the application of the internal standard method produced reproducible and precise measurements, the employment of internal standards in age estimation based on Asp racemization appears to provide quality assurance by avoiding possible errors arising from sample preparation.
authors.affiliation: Division of Forensic Sciences, Department of Social Medicine, Akita University School of Medicine, 1-1-1 Hondo, Akita 010, Japan. aszilvia@med.akita-u.ac.jp
authors.forename: Szilvia
authors.initials: S
authors.lastname: Arany
authors.forename: Susumu
authors.initials: S
authors.lastname: Ohtani
authors.forename: Naofumi
authors.initials: N
authors.lastname: Yoshioka
authors.forename: Kunio
authors.initials: K
authors.lastname: Gonmori
mesh_terms: D000293:Adolescent; D000328:Adult; D000366:Age Determination by Teeth / Q000379:methods*; D000368:Aged; D001224:Aspartic Acid / Q000032:analysis*; D002849:Chromatography, Gas; D003804:Dentin / Q000737:chemistry*; D005260:Female; D005553:Forensic Dentistry / Q000379:methods / Q000592:standards*; D006801:Humans; D016014:Linear Models; D008297:Male; D008715:Methionine / Q000032:analysis; D008875:Middle Aged; D009646:Norleucine / Q000032:analysis; D014092:Tooth Root / Q000737:chemistry*
chemical_list: D001224:Aspartic Acid; D009646:Norleucine; D008715:Methionine