Fluorescence determination of enantiomeric composition of pharmaceuticals via use of ionic liquid that serves as both solvent and chiral selector.
A new method has been developed for the sensitive and accurate determination of enantiomeric compositions of a variety of drugs, including propranolol, naproxen, and warfarin. The method is based on the use of the fluorescence technique to measure diastereomeric interactions between both enantiomeric forms of a drug with an optically active room temperature ionic liquid (RTIL) followed by partial least squares analysis of the data. The chiral RTIL used in this study, S-[(3-chloro-2-hydroxypropyl) trimethylammonium] [bis((trifluoromethyl)sulfonyl)amide] (S-[CHTA](+) [Tf(2)N](-)), is a novel chiral RTIL that has been synthesized successfully recently in our laboratory in optically pure form using a simple one-step reaction with commercially available reagents. The high solubility power and strong enantiomeric recognition ability make it possible to use this chiral RTIL to solubilize a drug and to induce diastereomeric interactions for the determination of enantiomeric purity, that is, to use it as both solvent and chiral selector. Enantiomeric compositions of a variety of pharmaceutical products with different shapes, sizes, and functional groups can be determined sensitively (microgram concentration) and accurately (enantiomeric excess as low as 0.30% and enantiomeric impurity as low as 0.08%) by use of this method.
Tran
Chieu D
CD
Department of Chemistry, Marquette University, Milwaukee, WI 53201, USA. chieu.tran@marquette.edu
Oliveira
Daniel
D
D007477:Ions; D009288:Naproxen / Q000032:analysis / Q000737:chemistry; D004364:Pharmaceutical Preparations / Q000032:analysis* / Q000737:chemistry*; D011433:Propranolol / Q000032:analysis / Q000737:chemistry; D000644:Quaternary Ammonium Compounds; D012997:Solvents; D013050:Spectrometry, Fluorescence / Q000379:methods; D013237:Stereoisomerism; D014859:Warfarin / Q000032:analysis / Q000737:chemistry
D007477:Ions; D004364:Pharmaceutical Preparations; D000644:Quaternary Ammonium Compounds; D012997:Solvents; D009288:Naproxen; D014859:Warfarin; D011433:Propranolol