Pitfalls in the use of breath pentane measurements to assess lipid peroxidation.

Literature values for breath pentane, an indicator of lipid peroxidation, vary by 1,000-fold in healthy subjects. This report describes multiple technical artifacts that may explain this disparity. First, we found that a major component of human breath (probably isoprene) co-eluted with pentane on columns used by some investigators, resulting in erroneously high determinations. Second, despite washouts using pentane-free air, ambient pentane dissolved in body fat may result in breath concentrations many times greater than that due to endogenous production. True endogenous breath pentane may never have been accurately determined.