Preparation of β-Cyclodextrin Capillary Column for Enantioseparation and Determination of Nicardipine and Manidipine by Capillary Electrochromatography

The separation and determination methods of calcium antagonists manidipine hydrochloride and nicardipine hydrochloride enantiomers were developed by open-tubular capillary electrochromatography( CEC),respectively. A new capillary column with p-nitrophenylcarbamation β-cyclodextrin was prepared by sol-gel method. The sol-gel modified with cyclodextrin derivative was characterized by infrared spectroscopy( IR) and scanning electron microscopy( SEM). In polar organic mode,the effect of the volume fraction and concentration of added triethylamine and glacial acetic acid,the content of organic solvents,the operating voltage,and temperature on the resolution( RS) were investigated. The optimized conditions were at 20 ℃,detection wavelength at 236 nm,and injection pressure at 3. 448 k Pa × 3 s. The compositions of mobile phases were V( Me OH) ∶ V( ACN) ∶ V( TEA) ∶ V( HOAc) = 57 ∶ 43 ∶ 0. 05 ∶ 0. 07 for manidipine hydrochloride and V( Me OH) ∶ V( ACN) ∶ V( TEA) ∶ V( HOAc) = 55 ∶ 45 ∶ 0. 05 ∶ 0. 08 for nicardipine hydrochloride. The resolution( Rs) of manidipine hydrochloride was 1. 39 at 25 k V. The resolution( Rs) of nicardipine hydrochloride was1. 30 at 20 k V. The RSDs of retention time and peak area were less than 1. 2% and 5. 6%( n = 5) for the drugs,respectively. It was indicated that new column has stable electrochromatography performance. The single run time were less than 5 min for manidipine hydrochloride and less than 7 min for nicardipine hydrochloride. Good linearity were observed in the concentration range of 5. 2 ~ 125. 0 mg / L with correlation coefficients 0. 9969 or more for both drug enantiomers. The limit of detection values were 1. 8 mg / L for manidipine and 2. 3 mg / L for nicardipine,respectively. The nitrophenyl carbamated β-cyclodextrin phase( NCDP) column were preliminarily used for determinations of manidipine hydrochloride and nicardipine hydrochloride tablet and capsule.