Chiral separation of nanomole amounts of alprenolol with cITP/NMR.
On-line cITP-NMR with chiral selectors separates and concentrates analytes and identifies host-guest interactions of analytes with selectivity enhancers in the electrolyte. An NMR microcoil designed for a 200 microm i.d. capillary creates a high-mass-sensitivity 30 nL NMR cell and is used as an on-line detector for cITP. Using a mixture of 2 nmol racemic alprenolol in acetate buffer with alpha-cyclodextrin and sulfated beta-cyclodextrin at pD 6.0, cITP-NMR successfully separates and concentrates both R- and S-alprenolol. The concentration enhancement for the R isomer is 224-fold and for the S isomer is 200-fold. The estimated concentration at peak maximum for R-alprenolol is approximately 28 mmol L(-1) and a slightly lower concentration, 25 mmol L(-1) is achieved for S-alprenolol. These concentrations convert to placing 76% of the injected S-alprenolol and 84% of the R-alprenolol into the 30 nL detection cell at peak maximum. With on-flow cITP-NMR, intermolecular interactions between the cyclodextrins and the alprenolol are observed in the NMR spectra. Aromatic and methyl moieties of R- and S-alprenolol are identified as two important sites that bind with these particular cyclodextrins.
Jayawickrama
Dimuthu A
DA
Department of Chemistry and the Beckman Institute, University of Illinois, 600 S Mathews Ave 63-5, Urbana, IL 61801, USA.
Sweedler
Jonathan V
JV
D000526:Alprenolol / Q000032:analysis* / Q000737:chemistry*; D003505:Cyclodextrins / Q000032:analysis / Q000737:chemistry; D004573:Electrolytes / Q000737:chemistry; D019075:Electrophoresis, Capillary / Q000379:methods; D006863:Hydrogen-Ion Concentration; D009682:Magnetic Resonance Spectroscopy / Q000379:methods; D008832:Microchemistry / Q000379:methods*; D008968:Molecular Conformation; D012680:Sensitivity and Specificity
D003505:Cyclodextrins; D004573:Electrolytes; D000526:Alprenolol