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Anal Chem. 2005 Apr 15;77(8):2348-61.

Identification of major histocompatibility complex-regulated body odorants by statistical analysis of a comparative gas chromatography/mass spectrometry experiment.

Author information

1
Pacific Northwest National Laboratory, 902 Battelle Boulevard, Richland, Washington 99354, USA. Alan.Willse@pnl.gov

Abstract

This paper examines the application of gas chromatography/mass spectrometry (GC/MS) in a comparative experiment to identify volatile compounds from urine that differ in concentration between two groups of inbred mice. A complex mixture might comprise several hundred or even thousands of volatile compounds. Because their number and location in a chromatogram are generally unknown, and because components overlap in populous chromatograms, the statistical problems offer significant challenges beyond traditional two-group screening procedures. We describe a statistical procedure to compare two-dimensional GC/MS profiles between groups, which entails (1) signal processing, baseline correction, and peak detection in single ion chromatograms; (2) aligning chromatograms in time; (3) normalizing differences in overall signal intensities; and (4) detecting chromatographic regions that differ between groups. In an application to chemosignaling, we detect differences in GC/MS chromatograms of ether-extracted urine collected from two inbred groups of mice that differ only in genes of the major histocompatibility complex (MHC). Several dozen MHC-regulated compounds are found, including two known mouse pheromones, 2,5-dimethylpyrazine and 2-sec-butyl-4,5-dihydrothiazole.

PMID:
15828767
DOI:
10.1021/ac048711t
[Indexed for MEDLINE]

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