(238a) Identification of Carbonyl Compounds in Exhaled Breath Using UHPLC-MS

The analysis of volatile organic compounds (VOCs) in exhaled breath for disease diagnosis has become a highly active research area. Carbonyl compounds including ketones and aldehydes in exhaled breath have been much investigated, since elevated levels of these compounds are considered as the potential biomarker for many types of diseases, including cardiovascular disease, chronic obstructive pulmonary diseases (COPD), lung cancer and COVID-19. Among all the developed methods for breath analysis, gas chromatography-mass spectrometry (GC-MS) is one of the most widely employed techniques. It allows separation and identification of compounds in the mixture. However, GC-MS requires sample pre-treatment (sampling and pre-concentration), which can lead to losses of analytes and contamination problems, and it’s not suitable for non-volatile compounds. In this work, we introduced a newly developed technology that combines an enhanced carbonyl trapping agent 2-(aminooxy)ethyl-N,N,N-trimethylammonium triflate (ATM) along with a microfabricated silicon microreactor to capture carbonyl compounds via oximation reactions. Ultra-high performance liquid chromatography-mass spectrometry (UHPLC-MS) was used for adducts separation and identification. Here, 3 groups of unsaturated aldehydes, including 2-alkenals (C_xH_2x-2O), 4-hydroxy-2-alkenals (C_xH_2x-2O₂), 4-hydroxy-2,6-alkadienals (C_xH_2x-4O₂) and 2 groups of saturated ketones and aldehydes, including aliphatic saturated aldehydes and ketones (C_xH_2xO) and aliphatic hydroxy saturated aldehydes and ketones (C_xH_2xO₂) have been separated and analyzed from exhaled breath samples. Some of these compounds have been reported relating to oxidative stress, and therefore, they are listed as biomarkers and the accurate measurement is important for disease detection as well as treatment. In this study, we identified these compounds in breath samples based on retention times, comparing with standards and tandem mass spectrometry.