Interfacing of CE in a PVP matrix to ion trap mass spectrometry: analysis of isomeric and structurally related (N-acetylamino)fluorene-modified oligonucleotides.

This work demonstrates the interfacing of capillary electrophoresis in a poly(N-vinylpyrrolidone) (PVP) solution to electrospray ionization ion trap mass spectrometry (ESI-ITMS). This methodology was used for on-line analysis of modified and unmodified oligonucleotides. Oligonucleotides were covalently modified using the model carcinogen 2-(N-acetoxy-N-acetylamino)fluorene. In the presence of PVP, separation was achieved for a set of isomeric (N-acetylamino)fluorene (AAF)-modified oligonucleotides differing only in their base sequences, while open-tube control experiments showed no separation between these compounds. The resolved analytes were identified by ESI-ITMS with negative ion detection. Online acquisition of MS and MS/MS data allowed unambiguous identification of all structural isomers. Baseline separation was also accomplished for a 10-compound mixture containing a series of five nonisomeric AAF-modified oligonucleotides and their unmodified parent oligonucleotides.