title: Analysis of amino acid 13C abundance from human and faunal bone collagen using liquid chromatography/isotope ratio mass spectrometry.
abstract: The scope of compound-specific stable isotope analysis has recently been increased with the development of the LC IsoLink which interfaces high-performance liquid chromatography (HPLC) and isotope ratio mass spectrometry (IRMS) to provide online LC/IRMS. This enables isotopic measurement of non-volatile compounds previously not amenable to compound-specific analysis or requiring substantial modification for gas chromatography/combustion/isotope ratio mass spectrometry (GC/C/IRMS), which results in reduced precision. Amino acids are an example of such compounds. We present a new chromatographic method for the HPLC separation of underivatized amino acids using an acidic, aqueous mobile phase in conjunction with a mixed-mode stationary phase that can be interfaced with the LC IsoLink for compound-specific delta13C analysis. The method utilizes a reversed-phase Primesep-A column with embedded, ionizable, functional groups providing the capability for ion-exchange and hydrophobic interactions. Baseline separation of 15 amino acids and their carbon isotope values are reported with an average standard deviation of 0.18 per thousand (n = 6). In addition delta13C values of 18 amino acids are determined from modern protein and archaeological bone collagen hydrolysates, demonstrating the potential of this method for compound-specific applications in a number of fields including metabolic, ecological and palaeodietary studies.
authors.affiliation: University of Oxford, Research Laboratory for Archaeology, Dyson Perrins Building, South Parks Road, Oxford OX1 3QY, UK. james.mccullagh@rlaha.ox.ac.uk
authors.forename: James S O
authors.initials: JS
authors.lastname: McCullagh
authors.forename: Dieter
authors.initials: D
authors.lastname: Juchelka
authors.forename: Robert E M
authors.initials: RE
authors.lastname: Hedges
mesh_terms: D000596:Amino Acids / Q000032:analysis* / Q000378:metabolism; D000818:Animals; D001106:Archaeology / Q000379:methods; D001842:Bone and Bones / Q000737:chemistry* / Q000378:metabolism; D002247:Carbon Isotopes / Q000032:analysis*; D002851:Chromatography, High Pressure Liquid; D003094:Collagen / Q000737:chemistry*; D049668:History, 15th Century; D006801:Humans; D013058:Mass Spectrometry / Q000295:instrumentation / Q000379:methods*
chemical_list: D000596:Amino Acids; D002247:Carbon Isotopes; D003094:Collagen