Stefanie Kellner
Chromatography coupled with tandem mass spectrometry (LC-MS/MS) is a highly sensitive method, which allows not only identification of modified nucleosides, but additionally fast and easy quantification in the single digit fmol (10-15 mol) region. Here, a triple quadrupole MS and the typical behavior of a modified nucleoside are shown.
The nucleoside elutes from the LC and enters the ion source, where it is charged with a proton on the nucleobase. The nucleoside then enters the first mass analyzer (quadrupole) and is fragmented in the collision cell at the glycosidic bond. After passing through the second mass analyzer (again: quadrupole), the charged nucleobase is detected in the electron multiplier and the mass spectrum is recorded.