| Title: | Extending PTR based breath analysis to real-time monitoring of reactive volatile organic compounds |
| Author(s): | Pugliese G; Trefz P; Brock B; Schubert JK; Miekisch W; |
| Address: | "Department of Anaesthesiology and Intensive Care, Rostock University Medical Center, Schillingallee 35, 18057 Rostock, Germany. wolfram.miekisch@uni-rostock.de" |
| ISSN/ISBN: | 1364-5528 (Electronic) 0003-2654 (Linking) |
| Abstract: | "Reactive exhaled volatile organic compounds (VOCs) such as nitrogen- and sulfur-containing substances may be related to diseases, metabolic processes and bacterial activity. As these compounds may interact with any surface of the analytical system, time-resolved monitoring and reliable quantification is difficult. We describe a proton transfer reaction time-of-flight mass spectrometry (PTR-ToF-MS) based analytical method for direct breath-resolved monitoring of reactive compounds. Aliphatic amines were used as test substances. Matrix adapted gas standards were generated by means of a liquid calibration unit. Calibration conditions were adapted in terms of materials, temperature and equilibration time. PTR-ToF-MS conditions were optimized in terms of inlet materials, transfer line and drift tube temperature and drift tube reduced electric field (E/N). Optimized PTR conditions in combination with inert materials and high temperatures considerably reduced the interactions of compounds with the surfaces of the analytical system. Good linearity (R2 > 0.99, RSDs < 5%) with LODs between 0.15 ppbV and 1.23 ppbV and LOQs between 0.24 ppbV and 1.94 ppbV could be achieved. The method was then applied to breath-resolved monitoring of reactive compounds in 17 healthy subjects after high and low oral protein challenge. Exhaled concentrations of trimethylamine, indole, methanethiol, dimethylsulfide, acetone, 2-propanol, 2-butanone and phenol showed significant changes after protein intake. Methanethiol concentrations increased 6-fold within minutes after the protein intake. Optimization of methods and instrument design enabled reliable breath-resolved PTR-MS based analysis of exhaled reactive VOCs in the sub-ppbV range. Continuous in vivo monitoring of exhaled amines and sulphur containing compounds may provide novel non-invasive insight into endogenous and gut bacteria driven protein metabolism" |
| Keywords: | "Adult Breath Tests/*methods Diet, High-Protein Diet, Protein-Restricted Female Humans Limit of Detection Male Mass Spectrometry/*methods Middle Aged Proof of Concept Study Volatile Organic Compounds/*analysis Young Adult;" |
| Notes: | "MedlinePugliese, Giovanni Trefz, Phillip Brock, Beate Schubert, Jochen K Miekisch, Wolfram eng England 2019/10/31 Analyst. 2019 Dec 2; 144(24):7359-7367. doi: 10.1039/c9an01478k" |
