Is endogenous isoprene the only coeluting compound in the measurement of breath pentane?

Pentane is a widely used index of lipid peroxidation. Although isopentane, an isomer of pentane, is a major component of ambient air in urban areas, m any Studies have disregarded the possibility that this compound is coeluted in the measurement of breath pentane. In the present study, a gas chromato graph equipped with a cold trap apparatus and a large-bore glass capillary column was used for determination of pentane, isopentane and isoprene in br eath and ambient air. Isoprene was detected in all subjects at a concentrat ion higher than that in the ambient air. However, the concentrations of bre ath pentane and isopentane were similar to, or less than, those of the ambi ent air. We suggest that great care is required in the measurement of breat h pentane so that endogenous isoprene and ambient isopentane are not coelut ed. (C) 2000 Elsevier Science B.V. All rights reserved.