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Nitrogen isotopic analyses by isotope-ratio-monitoring gas chromatography/mass spectrometryAmino acids containing natural-abundance levels of 15N were derivatized and analyzed isotopically using a technique in which individual compounds are separated by gas chromatography, combusted on-line, and the product stream sent directly to an isotope-ratio mass spectrometer. For samples of N2 gas, standard deviations of ratio measurement were better than 0.1% (Units for delta are parts per thousand or per million (%).) for samples larger than 400 pmol and better than 0.5% for samples larger than 25 pmol (0.1% 15N is equivalent to 0.00004 atom % 15N). Results duplicated those of conventional, batchwise analyses to within 0.05%. For combustion of organic compounds yielding CO2/N2 ratios between 14 and 28, in particular for N-acetyl n-propyl derivatives of amino acids, delta values were within 0.25% of results obtained using conventional techniques and standard deviations were better than 0.35%. Pooled data for measurements of all amino acids produced an accuracy and precision of 0.04 and 0.23%, respectively, when 2 nmol of each amino acid was injected on column and 20% of the stream of combustion products was delivered to the mass spectrometer.
Document ID
20040089706
Acquisition Source
Headquarters
Document Type
Reprint (Version printed in journal)
Authors
Merritt, D. A.
(Indiana University Bloomington, United States)
Hayes, J. M.
Date Acquired
August 21, 2013
Publication Date
January 1, 1994
Publication Information
Publication: Journal of the American Society for Mass Spectrometry
Volume: 5
ISSN: 1044-0305
Subject Category
Exobiology
Funding Number(s)
CONTRACT_GRANT: NAGW-1940
Distribution Limits
Public
Copyright
Other
Keywords
Non-NASA Center
NASA Discipline Exobiology

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