 A common technique to identify modifications in RNA and DNA is Liquid Chromatography with Mass Spectrometry or LC-MS. Mass spectrometry separates molecules by the mass and charge, while uridine and pseudrouidine has the same mass, but different charges.Liquid chromatography works by retention time, which has to do with leaving the column.A chemical way to identify pseudouridine uses a compound called CMC or N-cyclohexyl-N′-β-(4-methylmorpholinium) ethylcarbodiimide specifically label and distinguish Uridine from Pseudouridine.