Ion-pair reversed-phase thin-layer chromatography of basic drugs using sulphonic acids

The use of sulphonic acid ion-pair reagents in the thin-layer chromatography of four basic drugs (all secondary amines) on C18-bonded silica gel, paraffin coated silica gel and silica gel itself has been investigated. Effects of the ion-pair reagents were only obtained on C18-bonded silica gel, and only then when the reagents were pre-coated onto the stationary phase. In general the largest reductions in the RF values of the test compounds occurred when sodium dodecylsulphate was coated onto the plates.