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Peak measurement in gas chromatographic/mass spectrometric isotope studies
Author(s) -
Bluck L. J. C.,
Coward W. A.
Publication year - 1997
Publication title -
journal of mass spectrometry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.475
H-Index - 121
eISSN - 1096-9888
pISSN - 1076-5174
DOI - 10.1002/(sici)1096-9888(199711)32:11<1212::aid-jms580>3.0.co;2-9
Subject(s) - chemistry , chromatography , isotope , gas chromatography , mass spectrometry , analytical chemistry (journal) , environmental chemistry , nuclear physics , physics
A novel algorithm is described for the improved estimation of isotopomer ratios from gas chromatographic/mass spectrometric data. The minor isotopomer peak profile is fitted to an admixture of the major profile and its first and second derivatives. By this means allowance is made for non‐coincidence in the measurement of the two profiles. It is shown that a simple approximation for the derivative functions allows linear methods to be used to fit the digitized data for the minor to the data for the major and to that data shifted by one unit in both directions along the x‐axis. By including the x‐axis vector itself in the fit data superimposed on a linear baseline (i.e. with both slope and offset) can be accommodated. The algorithm has been tested with both simulated data and real data obtained from a commercially available instrument. In addition, the data were analysed by traditional summation estimates of spectral intensity and by fitting to a particular lineshape, the exponentially modified Gaussian. In all cases the proposed method is as good as, if not better than, the others, which, in conjunction with its simplicity, makes it a useful tool for the estimation of isotopomer ratios, with potential to improve precision of tracer techniques in metabolic studies. © 1997 John Wiley & Sons, Ltd.