Unusual retention behaviour of 4-substituted piperidines on polybutadiene and polystyrene coated zirconia by comparison to reverse phase silica

The retention properties of a range of N-methylated and N-des-methyl 4-substituted piperidines on polybutadiene (PBD) and polystyrene (PS) coated zirconia have been studied and compared to those of Xterra RP18 and Genesis C18 silica. The effect of buffer type and pH are investigated with regard to the elution order on all three stationary phases. The change in the elution order is linked to the degree of substitution of the piperidine nitrogen and appears to be independent of the rest of the structure, indicating that this moiety is most heavily involved in the separation mechanism on the zirconia phases.