Is NMR-based metabolomic analysis of exhaled breath condensate accurate?

Abstract

The metabolomic analysis of exhaled breath condensate (EBC) is a simple noninvasive approach for the study of respiratory system diseases. Previous studies introduced nuclear magnetic resonance (NMR)-based metabolomics as a method allowing a definite separation between healthy patients and patients with airway disease 1, 2. In these studies, the influence of external contaminants was also considered. de Laurentiis et al. 1 reported that the removal of interfering residual external contaminants was crucial for correct EBC analysis and they proposed a cleaning protocol for the “complete removal of the disinfectant signals” from the reusable parts of the condensers.

In order to verify the influence of the disinfectant signals we have compared the EBC 1H-NMR spectra of a healthy subject obtained after the standard cleaning protocol (disinfected for 15 min using a 1.5% Descogen™ solution and flushed for 15 min with water) recommended by the manufacturer’s guidelines and the International Consensus on EBC (fig. 1a) 3; one that was obtained after the cleaning protocol proposed by de Laurentiis et al. 1 (fig. 1b); and one obtained using a device without reusable condenser parts (fig. 1c). EBCs have been collected using an Anacon condenser (Biostec, Valencia, Spain). Sample collection and concentration (>99% water) were similar to those obtained in the procedure