Simultaneous determination of five saponins in Bupleuri Radix by HPLC-DAD dual wavelength method / 中国中药杂志

Epoxy ether type and isophthalene type saponin are the main saponins of Bupleurum chinense. However,due to the difference of their UV spectrum,there is no quantitative method for simultaneous determination of these two kinds of saponins. In this paper,a dual-wavelength high performance liquid chromatography(HPLC) was developed for simultaneous determination of five saponins in epoxidized ether(saikosaponin a,c,d) and isosorbide type(saikosaponin b1,b2). The mobile phase was eluted with acetonitrile-water(0.1% phosphoric acid) gradient at a column temperature of 30 °C and a flow rate of 1.0 mL·min⁻¹. The detection wavelengths were 208 nm for saikosaponins a,c, and d, and 254 nm for saikosaponins b₁ and b₂. The results showed that the separation of five kinds of saikosaponin was good, with the linear range of 9.70-1 935.00(=0.999 4),8.20-1 380.00(=0.999 3),6.90-1 640.00(=0.999 0),5.25-630.00(=0.999 4), and 5.15-618.00 mg·L⁻¹(=0.999 5), respectively. The average recoveries were 97.70%-100.2% and the RSD was less than 3%(=6). The method is simple,rapid and reproducible. It can be used for the determination of five kinds of saikosaponins in B. chinense.

Development and Validation of Dual Wavelength UV Spectrophotometric Method for simultaneous estimation of Cilnidipine and Olmesartan Medoxomil in Tablet dosage form.

A simple and economical dual wavelength spectrophotometric method has been developed for the simultaneous estimation of Cilnidipine and Olmesartan Medoxomil in their tablet dosage form. The principle for dual wavelength method is “the absorbance difference between two points on the overlain spectra is directly proportional to the concentration of the component of interest”. From the UV absorption spectrum of Cilnidipine, three wavelengths were selected, which were 282.99, 337.85 and 352.92 nm. At 352.92 nm only Cilnidipine has reasonable absorbance, so it was selected for the estimation of it from combination drug product. At these two wavelengths absorbance for Cilnidipine was found to be same i.e. absorbance difference was zero for any concentration, while for Olmesartan Medoxomil concomitantly increase in absorbance difference with increase in its concentration. So, 282.99 and 337.85 nm wavelengths were selected for the estimation of Olmesartan Medoxomil from its combination drug product. The method involved solving of an equation based on measurement of absorbances at two wavelengths 282.99 and 337.85 nm. Regression analysis of Beer’s plots showed good correlation in concentration range of 10-60 μg/ml for Cilnidipine and 20-120 μg/ml for Olmesartan Medoxomil. The suitability of this method was for quantitative determination of Cilnidipine and Olmesartan Medoxomil was proved by validation and recovery study. The proposed method was found to be simple, rapid, economical, accurate and reproducible for the routine analysis of both drugs in tablet dosage forms.

Two spectrophotometric methods for simultaneous determination of some antihyperlipidemic drugs / 药物分析学报

Two simple,accurate,precise and economic spectrophotometric methods have been developed for simultaneous determination of Atorvastatin calcium (ATR) and Ezetimibe (EZ) in their bulk powder and pharmaceutical dosage form.Method (Ⅰ) is based on dual wavelength analysis while method (Ⅱ) is the mean centering of ratio spectra spectrophotometric (MCR) method.In method (Ⅰ),two wavelengths were selected for each drug in such a way that the difference in absorbance was zero for the second drug.At wavelengths 226.6 and 244 nm EZ had equal absorbance values; therefore,these two wavelengths have been used to determine ATR; on a similar basis 228.6 and 262.8 nm were selected to determine EZ in their binary mixtures.In method Ⅱ,the absorption spectra of both ATR and EZ with different concentrations were recorded over the range 200-350,divided by the spectrum of suitable divisor of both ATR and EZ and then the obtained ratio spectra were mean centered.The concentrations of active components were then determined from the calibration graphs obtained by measuring the amplitudes at 215-260 nm (peak to peak) for both ATR and EZ.Accuracy and precision of the developed methods have been tested; in addition recovery studies have been carried out in order to confirm their accuracy.On the other hand,selectivities of the methods were tested by application for determination of different synthetic mixtures containing different ratios of the studied drugs.The developed methods have been successfully used for determination of ATR and EZ in their combined dosage form and statistical comparison of the developed methods with the reported spectrophotometric one using F and Student's t-tests showed no significant difference regarding both accuracy and precision.