3. RESULTS
3.1. Characterization of the urinary volatilome
The volatile composition of 132 urine samples was analysed using HS-SPME/GC-MS. Supplementary Figure S1 shows typical chromatographic profiles obtained for the control, COVID-19 patient, and recovered subject groups using HS-SPME/GC-MS methodology. Overall, a larger number of peaks with higher intensities were observed in the chromatographic profile of the COVID group than in the CTRL profile (Figure S1, supplementary Material). Furthermore, the number and intensity of peaks in the RECOV group were intermediate between those in the COVID and CTRL groups.
A total of 101 VOMs belonging to 13 chemical families were identified. Data regarding the VOMs detected in the analysed samples, frequency of occurrence, and mean relative peak areas are available in Supplementary Table S1. As shown in Figure 3, terpenes, phenolic compounds, norisoprenoids, and ketones were the main contributors to the urinary volatile profiles of the studied groups.