Polar embedded (PE) stationary phases that contain, among others, amide, carbamate and urea functionalities, have become a popular alternative to traditional octadecylsilane (C18) phases in modern HPLC method development schemes. The fundamental interactions that generate the alternative selectivity observed using the PE phases, however, remains unclear. Application data has suggested that PE phases, in general, preferentially retain neutral acidic and phenolic analytes when compared to C18 phases. This observation indicates that hydrogen bonding may play a significant role in the overall retention mechanism.
To best utilize PE stationary phases in intelligent method development protocols, it is imperative to understand the various contributions to overall retention. Only when these mechanisms of interaction are known can the analyst confidently control and manipulate retention and selectivity.
In this study, the contribution of the various mechanisms of interaction to retention on PE phases is examined through a number of chromatographic models. Linear solvation energy relationships (LSER) are used to explore the relative contributions of dispersive and polar interactions to retention. In addition, retention data is interpreted using recent column classification studies that focus on the various interaction terms that contribute to retention. The contribution of ionic interactions to retention on these phases is also briefly explored.
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Back to The 33rd Northeast Regional Meeting (July 14-17, 2005)