Determination of association constants between enantiomers of orciprenaline and methyl-β-cyclodextrin as chiral selector by capillary zone electrophoresis using a partial filling technique

Recent developments in chiral capillary electrophoresis and applications of this technique to pharmaceutical and biomedical analysis

“…Kodama et al [72] determined association constants between the enantiomers of aliphatic a-hydroxy acids and HP-b-CD, by calculating S DT (differential time selectivity coefficient = t mig(av) / Dt mig ) as a function of HP-b-CD concentration. In another study, binding strengths of orciprenaline enantiomers with methyl-b-CD were estimated applying the partial filling technique [82]. For estimation of association constants, it is assumed that mobility of the enantiomer-CD complexes are equal (m (R-CD) = m (S-CD) ), i.e., DK40.…”

“…During the run, both ends of the capillary are immersed into the BGE without chiral additive. The separation conditions are chosen in such a way that (i), the selector plug migrates away from the detector [130,180,200,201], (ii) the selector plug is stationary in the capillary [82,171], or (iii) the selector plug migrates slowly in the same direction as the enantiomers with the EOF or by its own mobility [202]. These conditions provide the possibility for enantiomers to be detected without any detection interferences.…”

“…The most recent applications of the PFT in chiral CE include, the use of tert-butylcarbamoylquinine [199], avidin analogues [203], 18C 6 H 4 [130], quail egg yolk riboflavin binding protein [201] and methyl-b-CD [69,82] as chiral selectors. Tert.-butylcarbamoylquinine dissolved in a nonaqueous BGE solution (ethanol-methanol, octanic acid and triethylamine) was used for enantiomeric separation of N-derivatized amino acids [199].…”

“…The PFT has also been applied to determine conditional association constants (K) and bioanalysis [82,178]. An important aspect of the PFT is the possibility to perform enantioseparations using different chiral selectors without introducing the chiral selectors into the mass spectrometer [130, 205±207].…”

“…CE methods have been developed not only to evaluate drug-related impurities and separation of drug substances of various structures [269] but also to determine physicochemical constants, such as pI, ionization constants (pK a ) [270,271] and association constants [65,72,47,82,178,272]. CE is generally considered as a complementary or alternative technique to HPLC for analysis of pharmaceuticals.…”