title: Biometrics from the carbon isotope ratio analysis of amino acids in human hair.
abstract: This study compares and contrasts the ability to classify individuals into different grouping factors through either bulk isotope ratio analysis or amino-acid-specific isotope ratio analysis of human hair. Using LC-IRMS, we measured the isotope ratios of 14 amino acids in hair proteins independently, and leucine/isoleucine as a co-eluting pair, to provide 15 variables for classification. Multivariate analysis confirmed that the essential amino acids and non-essential amino acids were mostly independent variables in the classification rules, thereby enabling the separation of dietary factors of isotope intake from intrinsic or phenotypic factors of isotope fractionation. Multivariate analysis revealed at least two potential sources of non-dietary factors influencing the carbon isotope ratio values of the amino acids in human hair: body mass index (BMI) and age. These results provide evidence that compound-specific isotope ratio analysis has the potential to go beyond region-of-origin or geospatial movements of individuals-obtainable through bulk isotope measurements-to the provision of physical and characteristic traits about the individuals, such as age and BMI. Further development and refinement, for example to genetic, metabolic, disease and hormonal factors could ultimately be of great assistance in forensic and clinical casework.
authors.affiliation: Department of Forensic and Investigative Science, West Virginia University, Morgantown, WV 26506-6121, USA; C. Eugene Bennett Department of Chemistry, West Virginia University, Morgantown, WV 26506, USA. Electronic address: glen.jackson@mail.wvu.edu.
authors.forename: Glen P
authors.initials: GP
authors.lastname: Jackson
authors.affiliation: Department of Chemistry and Biochemistry, Ohio University, Athens, OH 45701, USA.
authors.forename: Yan
authors.initials: Y
authors.lastname: An
authors.affiliation: C. Eugene Bennett Department of Chemistry, West Virginia University, Morgantown, WV 26506, USA.
authors.forename: Kateryna I
authors.initials: KI
authors.lastname: Konstantynova
authors.affiliation: Department of Chemistry and Biochemistry, Ohio University, Athens, OH 45701, USA.
authors.forename: Ayat H B
authors.initials: AH
authors.lastname: Rashaid
mesh_terms: D000293:Adolescent; D000328:Adult; D000367:Age Factors; D000368:Aged; D000596:Amino Acids / Q000032:analysis*; D015992:Body Mass Index; D002648:Child; D002675:Child, Preschool; D002853:Chromatography, Liquid; D005260:Female; D006197:Hair / Q000737:chemistry*; D006801:Humans; D007223:Infant; D008297:Male; D013058:Mass Spectrometry; D008875:Middle Aged; D055815:Young Adult
chemical_list: D000596:Amino Acids
keywords: Amino acids; Classification; Compound-specific isotope analysis (CSIA); Human hair; LC-IRMS