Chemical characterization of human breath

In the present work analysis of exhaled breath has been proposed as a novel way to detect disease, to monitor disease progression, and to monitor clinical intervention. An analytical method of analysis based upon two stages thermal desorption capillary gas chromatography and mass spectrometry was developed for the analysis of breath samples. All the steps of the analytical procedure were evaluated, trying to identify the critical aspects in order to optimize the entire procedure. A novel breath collection media has been developed that is cheap, disposable and readily available. This material allows breath samples to be collected in a novel manner. After validation the procedure was applied to real samples and preliminary experiments were performed aimed at estimating the variability of the composition of breath as a function of time of day and the inter-subject variability. In particular the trend in time of the two principal compounds in breath, acetone and isoprene was observed. The data showed a wide inter-variability between different people and also confirmed that a meal can influence breath composition. For this reason if possible, it was better to collect a breath sample in the morning before eating. Single substances or sets and patterns of exhaled markers were also investigated in order to establish correlations between the chemical composition of breath and patients’ clinical conditions. Preliminary studies were performed on patients with end-stage renal disease. The results underlined the capacity of the analytical procedure to appreciate small variation in breath composition. In particularly in people under dialysis treatment two compounds were found to show significant differences in breath concentration between patients and healthy people before the dialysis and no important differences after. These two compounds should become an additional and important parameter to determine the end of the dialysis treatment. In parallel a breath collection system prototype has been designed that enables samples of dead space air to be separated from end tidal breath and be collected independently. This device is also novel and has a great potential in breath analysis field.