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The Potential of Bulk and Amino-Acid Specific Isotope Ratio Mass Spectrometry of Human Hair in Forensic and Clinical Applications

An, Yan
http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1363701887

Abstract Details

2013, Doctor of Philosophy (PhD), Ohio University, Chemistry and Biochemistry (Arts and Sciences).
Isotope Ratio Mass Spectrometry (IRMS) is a specialized technique used to measure the isotopic ratios at natural abundance of the non-radioactive isotopes, and has proved to be a valuable tool in many applications. This research explores the use of IRMS of human hair for clinical and forensic applications. Several sample introduction methods are now available for commercial isotope ratio mass spectrometers. Combustion is most commonly used for bulk isotopic analysis, whereas gas and liquid chromatography are predominately used for the real-time isotopic analysis of specific compounds within a mixture. The current state-of-the-art method to study 13C/12C and 15N/14N isotopic ratio for a specific compound in complex biological samples is still gas chromatography-combustion-isotope ratio mass spectrometry (GC-C-IRMS). However, because the volatility and the polarity of the compounds, as well as the isotopic dilution and the kinetic isotopic effect, are complex issues for the GC separation, an alternative LC separation method coupled to the IRMS device (LC-IRMS) is presented in this work. Although the idea of combining the LC with isotope ratio mass spectrometry was proposed over 10 years ago, the interface allowing LC-IRMS coupling was only commercialized in 2004. This work indicates that currently more and more developments based on LC separation coupled, among others, to IRMS mass spectrometers are performed to measure 13C isotopic ratio of non-volatile compounds. We have started our experimental work by using the state-of-the-art method, GC-C-IRMS, for the simultaneous analyses of ten amino acids form human hair. Through the use of N,O-bis(trimethylsilyl) trifluoroacetamide (BSTFA) as a derivatizing agent, we were able to separate and analyze ten of the more abundant amino acids in human hair. EA-IRMS was used to analyze bulk isotope ratio of d13C, d15N and d34S values of human hair. Finally, we have applied LC-IRMS to measure amino acid in 20 different females from Jordan between the ages of 17 and 50 years. The preliminary studies suggest that for a relatively small sample size of 20 individuals, the subjects can be classified with a reasonable degree of confidence into groups related to body mass index, age and dietary habits. For leave-one-out cross-validated classification, cases were correctly assigned to their groups 77% of the time for BMI and 83% of the time for broad age groups. These time (length)-averaged amino-acid level d13C analyses enable such classification regardless of the short-term changes in each individual. The preliminary data warrant more work to be conducted on a larger and more diverse sample size to better support these initial observations. As we show, IRMS is a highly discriminating technique for distinguishing between hair samples from different human subjects. In the future, such biomarkers in human hair could be used as an instrumental method of analysis for the statistical comparison of known and questioned hair fibers, to provide physical or biometric information about the donor of a questioned hair sample, or as a biomarker for diagnosis in a clinical setting.
Glen Jackson (Advisor)
Shigeru Okada (Committee Chair)
Hao Chen (Committee Member)
Shiyong Wu (Committee Member)
154 p.
Analytical Chemistry; Clinical Psychology; Forensic Anthropology
Forensic science; human hair; amino acid; BSTFA; isotope ratio mass spectrometry; compound specific isotope ratios; bulk isotope ratios; gas chromatography; mass spectrometry; carbon isotope ratio; d13C; LC-IRMS

Recommended Citations

Citations

  • An, Y. (2013). The Potential of Bulk and Amino-Acid Specific Isotope Ratio Mass Spectrometry of Human Hair in Forensic and Clinical Applications [Doctoral dissertation, Ohio University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1363701887

    APA Style (7th edition)

  • An, Yan. The Potential of Bulk and Amino-Acid Specific Isotope Ratio Mass Spectrometry of Human Hair in Forensic and Clinical Applications . 2013. Ohio University, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1363701887.

    MLA Style (8th edition)

  • An, Yan. "The Potential of Bulk and Amino-Acid Specific Isotope Ratio Mass Spectrometry of Human Hair in Forensic and Clinical Applications ." Doctoral dissertation, Ohio University, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1363701887

    Chicago Manual of Style (17th edition)

ohiou1363701887
936
© 2013, some rights reserved.Creative Commons License The Potential of Bulk and Amino-Acid Specific Isotope Ratio Mass Spectrometry of Human Hair in Forensic and Clinical Applications by Yan An is licensed under a Creative Commons Attribution-NonCommercial-NoDerivs 3.0 Unported License. Based on a work at etd.ohiolink.edu.
This open access ETD is published by Ohio University and OhioLINK.