Sample preparation techniques for the determination of natural 15N/14N variations in amino acids by gas chromatography-combustion-isotope ratio mass spectrometry (GC-C-IRMS).
In order to identify natural nitrogen isotope variations of biologically important amino acids four derivatization reactions (t-butylmethylsilylation, esterification with subsequent trifluoroacetylation, acetylation and pivaloylation) were tested with standard mixtures of 17 proteinogenic amino acids and plant (moss) samples using GC-C-IRMS. The possible fractionation of the nitrogen isotopes, caused for instance by the formation of multiple reaction products, was investigated. For biological samples, the esterification of the amino acids with subsequent trifluoroacetylation is recommended for nitrogen isotope ratio analysis. A sample preparation technique is described for the isotope ratio mass spectrometric analysis of amino acids from the non-protein (NPN) fraction of terrestrial moss. 14N/15N ratios from moss (Scleropodium spec.) samples from different anthropogenically polluted areas were studied with respect to ecotoxicologal bioindication.
Hofmann
D
D
Department of Analytical Chemistry, UFZ Centre for Environmental Research Leipzig-Halle, Permoserstr 15, 04318 Leipzig, Germany.
Gehre
M
M
Jung
K
K
D000596:Amino Acids / Q000737:chemistry*; D044002:Bryophyta / Q000737:chemistry*; D004784:Environmental Monitoring / Q000379:methods; D004785:Environmental Pollutants; D008401:Gas Chromatography-Mass Spectrometry; D009587:Nitrogen Isotopes / Q000032:analysis; D013048:Specimen Handling
D000596:Amino Acids; D004785:Environmental Pollutants; D009587:Nitrogen Isotopes