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.