Real-time breath analysis of exhaled compounds upon peppermint oil ingestion by secondary electrospray ionization-high resolution mass spectrometry: technical aspects

Breath analysis by secondary electrospray ionization high-resolution mass spectrometry (SESI-HRMS) has potential for clinical diagnosis and drug monitoring. However, there is still a lack of benchmarking data that shows the capability of this technique and allows comparability with other breath analysis techniques. In this regard, the goal of this study was the identification of volatile compounds upon ingestion of a specific peppermint oil capsule to get benchmark data for real-time breath analysis with SESI-HRMS. This was done in the framework of a consortium set up by the International Association of Breath Research (IABR), aimed at comparing several analytical instruments for breath analysis. Breath temporal profiles of two subjects were analyzed with SESI-HRMS before and after ingestion of a peppermint oil capsule. The measurements were performed at two different locations using identical SESI-HRMS platforms to allow for comparability and benchmarking. Remarkably, along with the four major compounds (monoterpenes/cineole, menthone, menthofuran and menthol) reported by other members of the consortium, we detected 57 additional features significantly associated (ρ > 0.8) with the peppermint oil capsule, suggesting that this relatively simple intervention might trigger a more complex metabolic cascade than initially expected. This observation was made on both sites. Additional replicate experiments for one of the subjects suggested that a core of 35-40 unique molecules are consistently detected in exhaled breath upon ingestion of the capsule. In addition, we illustrate the analytical capabilities of real-time SESI-HRMS/MS to assist in the identification of unknown compounds. The results outlined herein showcase the performance of SESI-HRMS and enable comparison with other breath analysis techniques. Along with that, they strengthen the potential of this analytical technique for non-invasive drug monitoring and clinical diagnostic purposes.