title: Optimization of preparative electrophoretic chiral separation of ritalin enantiomers.
abstract: Continuous free flow electrophoresis (CFFE) was applied to the preparative chiral separation of ritalin enantiomers. Sulfated beta-cyclodextrin (sbeta-CD) was used as the chiral additive. Liquid chromatography-mass spectrometry (LC-MS) experiments were applied to study the time averaged concentration of sbeta-CD in the separation chamber. The distribution of sbeta-CD in the separation chamber greatly influenced resolution and the angle of deflection. To optimize the separation, several parameters (methanol, concentration of sbeta-CD in the cathodic wash and in the separation buffer, and the introduction of a low conductivity zone) were investigated. The dependence of the resolution and deflection angles of ritalin enantiomers on the concentration of sbeta-CD in both the separation buffer and in the cathode wash solution appeared to be non-linear. Under close to optimal conditions, resolution of ritalin enantiomers was about 0.8 with an average processing rate of 0.5 mg/h. Overall, the enantiomeric purity of the individual isomers was approximately 83%; however, of the 20 vials containing ritalin, the presence of both enantiomers was only detected in three vials.
authors.affiliation: Department of Chemistry, University of Cincinnati, PO Box 210172, Cincinnati, OH 45221-0172, USA.
authors.forename: Eva
authors.initials: E
authors.lastname: Schneiderman
authors.forename: Samuel R
authors.initials: SR
authors.lastname: Gratz
authors.forename: Apryll M
authors.initials: AM
authors.lastname: Stalcup
mesh_terms: D000697:Central Nervous System Stimulants / Q000032:analysis*; D004586:Electrophoresis / Q000295:instrumentation / Q000379:methods; D008774:Methylphenidate / Q000032:analysis*; D013237:Stereoisomerism
chemical_list: D000697:Central Nervous System Stimulants; D008774:Methylphenidate