Is pentane a normal constituent of human breath?

Breath analysis is a non-invasive method for investigation of the volatile compounds produced by humans. Pentane has often been taken as an indicator of lipid peroxidation. Our purpose in this study was to determine its normal concentration in the breath of healthy humans. Using a specific and sensitive gas chromatography-mass spectrometry technique pentane concentrations in breath were lower than 10 pmoles/l. The high levels of pentane found by some authors in healthy humans were probably due to the coelution of pentane with isoprene, a volatile hydrocarbon present in human breath.