RETENTION BEHAVIOUR OF BASIC AZAARENES IN REVERSED-PHASE HPLC ON OCTADECYLSILICA STATIONARY PHASES
| Authors | |
|---|---|
| Year of publication | 2004 |
| Type | Article in Proceedings |
| Conference | 27th international symposium on Capillary chromatography |
| MU Faculty or unit | |
| Citation | |
| Field | Analytic chemistry |
| Keywords | azaarenes; octadecylsilica stationary; retention behaviour |
| Description | The retention behaviour of two- and three-ring azaarenes on octadecylsilica stationary phases has been studied. The experiments were carried out with eight basic azaarenes-acridines under isocratic elution conditions using buffered mobile phase with 60 % (v/v) of methanol. The effect of the varying mobile phase pH and the buffer concentration on the solute retention has been investigated over a range of eluent pH from 2,5 to 7,5. The retention behaviour of the acridines was evaluated with respect to their hydrophobicity (log KOW), acid-base properties (pKA) and regarding the surface properties of the selected stationary phases. Purospher Star RP 18e (Merck) and Zorbax Eclipse XDB-C18 (Agilent Technologies) were tested (Engelhardt, Galushko) to determine the column silanole activity and hydrophobicity. The Purospher Star RP 18e higher both silanole activity and hydrophobicity than the Zorbax Eclipse XDB-18 has shown. The retention as a function of eluent pH was evaluated using equations based on solute ionisation. Serious deviations from the theory for all tested acridines were observed. It is a confirmation of their complex retention mechanism in which not only hydrophobic but also other interactions participate. Anomalous retention patterns of some acridines in low eluent pH (<3,5) with different buffer concentrations has been observed. This is probably related with the presence of the positively charged sites existing on the tested phases in low mobile-phase pH with low ionic strength. The elution behaviour within acridines of uniform hydrophobicities has shown to be directly correlated with their acid-base properties, corresponding to their potentials for silanophilic interactions: isomers with higher pKA values were less retained. |
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