A versatile chiral selector for determination of enantiomeric composition of fluorescent and nonfluorescent chiral molecules using steady-state fluorescence spectroscopy

A fluorescent chiral molecular micelle (FCMM), poly (sodium N-undecanoyl-L-phenylalaninate) (poly-L-SUF), was developed as a chiral selector for enantiomeric recognition and determination of enantiomeric composition of four fluorescent and four nonfluorescent chiral molecules by use of steady-state fluorescence spectroscopy. The influence of FCMM concentration, buffer pH and complexation medium on FCMM-analyte host-guest complexation, and the emission spectral properties of the resulting complexes were investigated. The chiral interactions of the analytes,1,1'-binaphthyl-2,2'-diamine, 1-(9-anthryl)-2,2,2-trifluoroethanol, propranolol, naproxen, chloromethyl menthyl ether (CME), citramalic acid, tartaric acid, and limonene (LIM), in the presence of poly-L-SUF were based on diastereomeric complex formation. The figures of merit obtained from the partial-least-squares regression modeling of the calibration samples suggested good prediction ability for the validation of six of the eight chiral analytes. Better host-guest complexation of the more hydrophobic molecules, CME and LIM, were obtained in methanol/water mixtures, resulting in better predictability of the regression models. Prediction ability of the models was evaluated by use of the root-mean-square percent relative error (RMS%RE) and was found to range from 1.77 to 15.80% (buffer), 1.26 to 7.95% (25:75 methanol/water), and 1.21 to 4.28% (75:25 methanol/water).     

Enantiomeric composition analysis of pranoprofen in equine plasma and urine by chiral liquid chromatography-tandem mass spectrometry in selected reaction monitoring mode

The enantioseparation of pranoprofen after its addition in racemic form into equine plasma and urine was conducted by chiral liquid chromatography-tandem mass spectrometry in selected reaction monitoring mode. The methods for the assay of both enantiomers were linear (r≥0.9943) in the low range from 0.001 to 0.1μg/mL and high range from 0.01 to 1.0μg/mL with good precision (% RSD≤5.6) and accuracy (% RE=-5.3 to 1.9). When racemic pranoprofen was orally administered to four horses at a single dose of 3.1mg/kg, the median plasma concentrations of (R)-pranoprofen were lower than the levels of (S)-pranoprofen from start to finish. In contrast, the urinary level of (R)-pranoprofen was 2.5 fold higher than (S)-pranoprofen level for the first 6h, followed by its rapid decrease down below (S)-pranoprofen concentration. Monitoring of the R/S ratios in equine urine may be useful for the prevention of false positive in horse doping test.