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Determination of calcium dobesilate in human plasma using ion-pairing extraction and high-performance liquid
1Department of Internal Medicine, Faculty of Health Sciences, Semmelweis University, Budapest, Hungary. rona@hiete.hu
Abstract:
A rapid, simple reversed-phase high-performance liquid chromatographic method with ultraviolet absorbance detection has been developed for the determination of calcium dobesilate in human plasma. Sample processing is based on an ion-pairing extraction with tetra-n-butylammonium hydroxide as cationic pairing ion and dichloromethane. Separation of the investigated calcium dobesilate and 2,4-dihydroxybenzoic acid as internal standard was achieved on a Discovery RP-Amide C16 analytical column with 50 mM, pH 2.5, potassium dihydrogenphosphate buffer-acetonitrile (75:25, v/v) mobile phase. The wavelength was set at 305 nm. The limit of quantitation is 100 ng/ml and the calibration curve is linear up to 50 microg/ml. Within-day and between-day precision expressed as the relative standard deviation is about 10% and the accuracy of the determination did not deviate from 100% by more than +/-10%. The developed method was found to be suitable for application in human bioequivalence studies.