Determination of the binding constants of modafinil enantiomers with sulfated β-cyclodextrin chiral selector by capillary electrophoresis using three different linear plotting methods.
Binding constants for the enantiomers of modafinil with the negatively charged chiral selector sulfated-β-CD (S-β-CD) using CE technique is presented. The calculations of the binding constants employing three different linearization plots (double reciprocal, X-reciprocal and Y-reciprocal) were performed from the electrophoretic mobility values of modafinil enantiomers at different concentrations of S-β-CD in the BGE. The highest inclusion affinity of the modafinil enantiomers were observed for the S-enantiomer-S-β-CD complex, in agreement with the computational calculations performed previously. Binding constants for each enantiomer-S-β-CD complex at different temperatures, as well as thermodynamic parameters for binding, were calculated. Host-guest binding constants using the double reciprocal fit showed better linearity (r(2)>0.99) at all temperatures studied (15-30°C) and compared with the other two fit methods. The linear van't Hoff (15-30°C) plot obtained indicated that the thermodynamic parameters of complexation were temperature dependent for the enantiomers.
Al Azzam
Khaldun M
KM
School of Chemical Sciences, Universiti Sains Malaysia, Penang, Malaysia.
Saad
Bahruddin
B
Aboul-Enein
Hassan Y
HY
D001559:Benzhydryl Compounds / Q000737:chemistry*; D019075:Electrophoresis, Capillary / Q000379:methods*; D007700:Kinetics; D016014:Linear Models; D000077408:Modafinil; D013237:Stereoisomerism; D013431:Sulfates / Q000737:chemistry; D013816:Thermodynamics; D047392:beta-Cyclodextrins / Q000737:chemistry*
D001559:Benzhydryl Compounds; D013431:Sulfates; D047392:beta-Cyclodextrins; D000077408:Modafinil