Analysis of volatile organic compounds: possible applications in metabolicdisorders and cancer screening

The human breath contains a variety of endogenous volatile organic compound s (VOCs). The origin and pathophysiological importance of these VOCs is poo rly investigated. Little is known about the interaction of VOCs from ambien t air, such as those produced by plants and exhaust fumes, with the human o rganism. Gas chromatographic determination of VOC concentrations is tedious . Proton-transfer-mass spectroscopy (PTR-MS), a new technology for the onli ne detection of VOC patterns, is a valuable alternative. We present two interesting molecular species, isoprene and ortho to) -tolui dine, as examples of endogenously produced VOCs. In a case study, breath is oprene reductions during lipid-lowering therapy (36%) were shown to correla te with cholesterol (32%) and LDL concentrations (35%) in blood (p < 0.001) over a period of 15 days. Therefore, isoprene concentrations in human brea th (measured by PTR-MS) might serve as an additional parameter to complemen t invasive tests for controlling lipid-lowering therapy. Furthermore, it ma y be a useful parameter for lipid disorder screening. Mass-108, which presu mably represents o-toluidine in our breath samples, was found in significan tly higher concentrations in the breath of patients with different tumors ( 1.5 <plus/minus> 0.8 ppbv) than in age-matched controls (0.24 +/- 0.1 ppbv, p < 0.001). Inflammatory reactions do not seem to alter the pattern of mas s-108. Therefore, it appears to be a currently underestimated carcinoma mar ker that deserves further investigation.