Pentane and isoprene in expired air from humans: gas-chromatographic analysis of single breath.
Both pentane and isoprene are excreted in human breath. Although pentane is considered an index of lipid peroxidation, the significance of isoprene is unknown. Having a similar boiling point, these two hydrocarbons are difficult to separate by gas chromatography. We separated pentane from isoprene on both a Poraplot Q and a Poraplot U column, injecting single-breath samples directly into a gas chromatograph. The breath samples were pressurized to 800 mmHg to increase the amount of sample volume delivered to the column. In a group of 43 healthy volunteers, the concentrations of end-expiratory pentane and isoprene were 0.57 +/- 0.3 and 7.05 +/- 3.53 nmol/L, respectively. There was a significant linear correlation (r = 0.57, P < 0.0001) between age and pentane concentration in expired air; isoprene showed no correlation with age or pentane concentrations. The age-related increase in pentane production suggests that oxidative stress may play a role in the aging process in humans. The method described should allow for rapid, inexpensive, serial measurement of expired pentane and isoprene.
Mendis
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Department of Medicine/Cardiology, Loyola University Medical Center, Maywood, IL 60153.
Sobotka
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PA
Euler
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D000328:Adult; D000368:Aged; D000375:Aging; D001944:Breath Tests / Q000379:methods*; D002070:Butadienes / Q000032:analysis*; D002849:Chromatography, Gas / Q000379:methods*; D005260:Female; D045782:Hemiterpenes; D006801:Humans; D008297:Male; D008875:Middle Aged; D010420:Pentanes / Q000032:analysis*; D012016:Reference Values; D012044:Regression Analysis
D002070:Butadienes; D045782:Hemiterpenes; D010420:Pentanes; C005059:isoprene; C033353:pentane