CORESTA Meeting, Smoke/Technology, Vienna, 1995, ST28

Evaluation of micellar electrokinetic capillary chromatography for the analysis of tobacco alkaloids

Philip Morris USA, Research Center, Richmond, VA, USA
It has been demonstrated that capillary zone electrophoresis (CZE) can be used for the determination of nicotine in tobacco. Under certain circumstances, nicotine analyses can be accomplished within a time period as short as 100 seconds. Simultaneous determination of several common alkaloids ( i.e. , nicotine, nornicotine, myosmine, anatabine and anabasine) in tobacco, however, require further work. Separation of these alkaloids which differ only slightly in molecular structure (e.g., a double bond) from the complex sample matrix of tobacco represents an analytical challenge. Initial efforts of adding organic solvents to enhance the effect of electrophoresis and thus resolution of the CZE procedure produce limited success. Satisfactory separation of the five alkaloids from a tobacco sample was achieved after introducing an ionic surfactant into the CZE buffer system at a concentration above its critical micellar concentration. This chromatographic method which utilizes the technique of CZE with the addition of a micellar phase is termed as "micellar electrokinetic capillary chromatography" (MECC). Solutes are separated based on their differential partitioning between an electroosmotically driven aqueous phase and a slower moving, electrophoretically retarded micellar phase. Tobacco samples were extracted 10 minutes with sonication into a 1% triethanolamine in water. Separation was performed in an uncoated fused-silica capillary. Resolution and selectivity were influenced by experimental parameters such as applied voltage, pH value, buffer composition and surfactant concentration. UV absorption of alkaloids were enhanced in the presence of micelles as a function of the surfactant concentration.