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Combined Isotopic Analysis of Nanogram Quantities of Atmospheric Methane
Author(s) -
Morse Andrew D.,
Morgan G. H.,
Butterworth A. L.,
Wright I. P.,
Pillinger C. T.
Publication year - 1996
Publication title -
rapid communications in mass spectrometry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.528
H-Index - 136
eISSN - 1097-0231
pISSN - 0951-4198
DOI - 10.1002/(sici)1097-0231(199611)10:14<1743::aid-rcm762>3.0.co;2-r
Subject(s) - methane , chemistry , isotopomers , atmospheric methane , analytical chemistry (journal) , isotopologue , mass spectrometry , yield (engineering) , environmental chemistry , chromatography , organic chemistry , molecule , thermodynamics , physics
Stable isotope measurements are increasingly utilized to constrain global budgets of atmospheric trace gases. Published analytical techniques for studying the parallel stable isotopic composition of methane (δ 13 C and δD) require prohibitively large quantities of methane for analysis. In a break from convention, a static mass spectrometer has been developed to use aliquots of methane as the analyte. These measurements yield the relative abundances (δ 17 M, ‰) of the major isotopomers of methane ( 13 CH + 4and 12 CDH + 3 ) with 12 CH + 4 . Analyses of 0.5 nmol samples of NGS standards have shown that δ 17 M can be determined with a precision of ±0.2‰. If the δ 13 C of the sample is known then δD may be calculated from the measured δ 17 M. Calculations show that a precision of 0.2‰ for δ 17 M is equivalent to measuring δD with a precision of ± 3.6‰ (cf. ±2–3‰ by conventional means). Where δ 13 C is not known, then δ 17 M still provides useful information on methane sources, in effect combining δ 13 C and δD.