title: Isolation and desalting with cation-exchange chromatography for compound-specific nitrogen isotope analysis of amino acids: application to biogeochemical samples.
abstract: We have established a procedure for removing interfering materials from extracts of geological and biological samples, in order to determine precise compound-specific nitrogen isotopic compositions of amino acids. We employed cation-exchange chromatography of protein and non-protein amino acids prior to derivatization for gas chromatographic separation. The average recovery of a standard amino acid solution was better than 94%, without nitrogen isotope fractionation during the cation-exchange chromatography. We applied the procedure to various environmental samples including 'hard' (calcareous, siliceous, rock and sediment samples) and 'soft' materials (aggregated microbial samples and biological soft tissue samples). We conclude that cation-exchange chromatography is a pre-treatment procedure which should be widely useful for the determination of compound-specific nitrogen isotopic compositions of amino acids.
authors.affiliation: Institute of Biogeosciences, Japan Agency for Marine-Earth Science and Technology, 2-15 Natsushima, Yokosuka, Kanagawa 237-0061, Japan. takano@jamstec.go.jp
authors.forename: Yoshinori
authors.initials: Y
authors.lastname: Takano
authors.forename: Yuichiro
authors.initials: Y
authors.lastname: Kashiyama
authors.forename: Nanako O
authors.initials: NO
authors.lastname: Ogawa
authors.forename: Yoshito
authors.initials: Y
authors.lastname: Chikaraishi
authors.forename: Naohiko
authors.initials: N
authors.lastname: Ohkouchi
mesh_terms: D000596:Amino Acids / Q000032:analysis* / Q000302:isolation & purification; D000818:Animals; D001419:Bacteria / Q000737:chemistry; D002411:Cation Exchange Resins / Q000737:chemistry; D002852:Chromatography, Ion Exchange / Q000295:instrumentation / Q000379:methods*; D056890:Eukaryota / Q000737:chemistry; D009587:Nitrogen Isotopes / Q000032:analysis* / Q000302:isolation & purification; D010944:Plants / Q000737:chemistry
chemical_list: D000596:Amino Acids; D002411:Cation Exchange Resins; D009587:Nitrogen Isotopes