Separation of nicotine and nornicotine enantiomers via normal phase HPLC on derivatized cellulose chiral stationary phases

Abstract

This paper describes the enantiorecognition of (±)nicotine and (±)nornicotine by high-performance liquid chromatography using two derivatized cellulose chiral stationary phases (CSPs) operated in the normal phase mode. It was found that different substituents linked to the cellulose backbone significantly influence the chiral selectivity of the derivatized CSP. The results showed that, in general, the tris(4-methylbenzoyl) cellulose CSP (Chiralcel OJ) surpasses tris(3,5-dimethylphenyl carbamoyl) cellulose CSP (Chiralcel OD). On the former column, the resolution (±)nicotine and (±)nornicotine enantiomers depended largely on mobile phase compositions. For the separation of the nicotine enantiomers, the addition of trifluoroacetic acid to a 95:5 hexane/alcohol mobile phase greatly improved the enantioresolution, probably due to enhanced hydrogen bonding interactions between the protonated analytes and the CSP. For (±)nornicotine separation, a reduction in the concentration of alcohol in the mobile phase was more effective than the addition of trifluoroacetic acid. Possible solute-mobile phase-stationary phase interactions are discussed to explain how different additives in the mobile phase and different substituents on the cellulose glucose units of the CSPs affect the separation of both pairs of enantiomers. Chirality 10:364–369, 1998. Published 1998 Wiley-Liss, Inc.