Mass spectrometry nitrogen isotope ratio determination

Gas chromatography/combustion/isotope ratio mass spectrometry (CSIA) was used to determine the stable isotope composition of amino acid enantiomers by nitrogen isotope analysis [660]. 

Finally, the del value is zero when the sample and the standard have the same isotopic composition. The international standards for O, C, H, N, and S are Standard Mean Ocean Water (SMOW), Pee Dee Belemnite (PDB) carbonate fossil, SMOW, atmospheric nitrogen (N2), and the Canyon Diablo Triolite (CDT) iron meteorite, respectively (table 7.6 Fame, 1986). More specifically, the13C/12C of natural materials and standards is determined using isotope-ratio mass spectrometry (for details, see Hayes, 1983 Boutton, 1991). 

Owens, N. J. P., and Rees, A. P. (1989). Determination of nitrogen-15 at sub-microgram levels of nitrogen using automated continuous-flow isotope ratio mass spectrometry. Analyst 114, 1655-1657. 

CF-IRMS Continuous flow-isotope ratio mass spectrometry. A procedure that uses an instrument that is capable of repeatedly and rapidly measuring the masses of selected gases (e.g., carbon dioxide, hydrogen, nitrogen) delivered in a continuous gas stream from another instrument, such as an elemental analyzer or a gas chromatograph, to determine their isotopic compositions. 

Molinie R, Kwiecien RA, Silvestre V, Robins RJ (2009) Determination of nitrogen-15 isotope fractionation in tropine evaluation of extraction protocols for isotope ratio measurement by isotope ratio mass spectrometry. Rapid Commun Mass Spectrom 23 (Copyright (C) 2012 American Chemical Society (ACS). All Rights Reserved.) 4031 1037. doi 10.1002/ rcm.4344... 

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