Application of molecularly imprinted polymers in supercritical fluid chromatography

Molecularly imprinted polymers (MIPs), for the templates free base racemic propranolol and the L-enantiomer of phenylalanine anilide (L-PA), were inve stigated as stationary phases in supercritical fluid chromatography (SFC). Large retention differences were observed on the propranolol MIP for both t he template molecule and the structural analogue metoprolol compared to tha t observed on the corresponding blank polymer. Mobile phase composition and solute concentration were found to affect this retention behaviour. The ph enylalanine anilide MIP (L-PA MIP) was found to be enantioselective in SFC with stronger retention observed for the template enantiomer. Throughout th e study, characteristic imprinting peak shapes for the stronger retained te mplate molecule were observed for both MIPs examined. After a number of day s under supercritical fluid conditions, the performance of the photochemica lly initiated L-PA MIP was found to significantly deteriorate whereas the t hermally initiated propranolol MIP revealed only small changes in its separ ation performance after a long term of operation. The separation behaviour of these two MIPs in SFC was compared with results obtained on the same col umns in high-performance liquid chromatography (HPLC) both before and after their application in SFC. (C) 2000 Elsevier Science B.V. All rights reserv ed.