Identification of MDA associated clusters in exhaled breath samples of patient measurements from GC-IMS spectra

Introduction: There is a great need to make an non-invasive assessment of the metabolism. Previous publications reported evidence of MDA in the breath condensate as a marker of oxidative stress. In a pilot study, it should be checked whether MDA using GC-IMS as a single breath method is immersion. Methods: A GC-IMS of STEP was used for the investigations. The system combines a multi capillary column with an ion mobility spectrometer. Spectra of the reference substance for MDA and breath samples from subjects with moderate physical exertion were measured. The comparable peaks of the reference and the air were determined by means of cluster analysis-based software. The classification has been carried out with a leave-one-out cross validation and support vector machine. Results: It could be shown that identical peaks such as for reference measurements even in exhaled air of subjects are identifiable. Thus, it appears that MDA is measurable also bypassing the breath condensate directly out of the exhaled air. Figure 1: Cluster 49 of 391 compared the MDA reference (9) to air before (11) or to moderate exercise (12). Conclusions: It became evident that there is a sufficient sensitivity for measuring of MDA with the GC IMS. Further investigations must show if found parameters of oxidative metabolism and the metabolism of unsaturated fatty acids can be used to track metabolic alterations during exercise.