Fig. 3. Schematic illustration of the procedure for determination of uridine modifications by CMCT labelling coupled with LC-ESI-MS/MS analysis. Isolated RNA was enzymatically digested followed by CMCT labelling. Then the CMCT labelled uridine modifications were extracted and enriched by CeO₂ solid phase extraction (SPE). The resulting CMCT labelled uridine modifications were subjected to LC-ESI-MS/MS analysis.