Retention Behavior of Pyridinium Oximes on PFP Stationary Phase in High-Performance Liquid Chromatography.

The chromatographic behavior was studied of a series of potential acetylcholinesterase reactivators, pyridinium oximes, bearing linear aliphatic chains of the length of the aliphatic bridge from 1 to 12 carbon atoms, on a pentafluorophenyl-modified stationary phase. The retention mechanisms and the dependence of the capacity factor on mobile phase composition, aliphatic chain bridge length and calculated log P were evaluated and discussed in detail. The separation of the studied oximes was found to be driven by hydrophobic interactions when a lower content of organic modifier was used in mobile phase; however, the ion-exchange mechanism was the leading one when a large portion of organic modifier was used. In addition, the lipophilicity was found to be a driving mechanism of the separation of oximes bearing a connecting chain of the length of 6–12 carbon atoms, whereas the retention of oximes with shorter connecting chains was significantly influenced by other separation mechanisms such as aromatic or π–π interaction. These results can be useful for the development of new, efficient acetylcholinesterase reactivators. [ABSTRACT FROM AUTHOR]