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Ion-pair reversed-phase thin-layer chromatography of basic drugs using sulphonic acids
1Department of Safety of Medicines, I.C.I. Pharmaceuticals Division, Macclesfield, Cheshire, U.K.
Journal of Chromatography
|June 10, 1988
Summary
Sulfonic acid ion-pair reagents improve thin-layer chromatography for basic drugs on C18-bonded silica. Pre-coating these reagents onto the stationary phase, especially sodium dodecylsulphate, significantly reduced retention factor values.
Area of Science:
- Analytical Chemistry
- Chromatography
Background:
- Thin-layer chromatography (TLC) is a common separation technique.
- Basic drugs, often secondary amines, present challenges in TLC analysis.
- Ion-pair chromatography is a method to improve separation of ionic compounds.
Purpose of the Study:
- To investigate the efficacy of sulfonic acid ion-pair reagents in TLC of basic drugs.
- To evaluate the impact of different stationary phases and reagent application methods.
Main Methods:
- Thin-layer chromatography was performed on C18-bonded silica gel, paraffin-coated silica gel, and bare silica gel.
- Sulfonic acid ion-pair reagents were tested for their effect on retention.
- Reagents were applied by pre-coating the stationary phase.
Main Results:
- Ion-pair reagent effects were observed exclusively on C18-bonded silica gel.
- Pre-coating the stationary phase with ion-pair reagents was essential for observing effects.
- Sodium dodecylsulphate demonstrated the most significant reduction in retention factor (RF) values for the basic drugs.
Conclusions:
- Sulfonic acid ion-pair reagents are effective for improving TLC of basic drugs, specifically on C18-bonded silica.
- Pre-coating the stationary phase is a critical factor for successful ion-pair TLC.
- Sodium dodecylsulphate is a promising ion-pair reagent for this application.