Molecularly imprinted polymers as tools for the screening of felodipine from dihydropyridine calcium antagonists by pressurized capillary electrochromatography

A group of structurally similar dihydropyridine calcium antagonists (DHPs) and related compounds were used to simulate a combinatorial library. A molecularly imprinted polymer (MIP) comprising felodipine (FLD) was synthesized in situ inside the capillary for use in the separation of FLD from other DHPs by pressurized electrochromatography (pCEC). To evaluate the feasibility of using the MIP columns for the separation of FLD, parameters including pH, the applied voltages, and the effect of organic modifier were studied. The results indicated that the MIP columns demonstrated better recognition properties over a pH range of 4–6. The efficiency (plates/m) at pH 5.0 for the non-imprinted analytes was 117,000 for thiourea, 18,700 for nicarpidine, 17,300 for nisoldipine, and 14,600 for nifedipine; however, the efficiency for the imprinted analyte FLD was low, as evidenced by the broad peak, yielding only 5,100 plates/m. The column efficiency was also investigated under both micro-HPLC and pCEC conditions.