Abstract
An ion-pairing high-performance liquid chromatographic method was developed for the determination of yohimibine and strychnine in dosage forms. The mobile phase consists of methanol-water-acetic acid-triethylamine (50 : 50 : 1 : 0.3) with 1 mM sodium hexanesulfonate as the counter-ion. The analysis was carried out using an octadecyl silica (5 μm, 100 mm × 6 mm i.d.) column. Detection was done spectrophotometrically at 254 nm. Calibration graphs were rectilinear over the concentration ranges of 2-20 μg/ml for strychine sulfate and 5-50 μg/ml for yohimbine HCl, with minimum detection limits of 0.1 and 0.4 μg/ml, respectively. For the determination of yohimbine alone, high performance liquid chromatography/fluorometric analysis (Ex270, Em<360>nm) was carried out with the same mobile phase. THe calibration graph was rectilinear over the concentration range of 5-40 ng/ml with a minimum detection limit of 2 ng/ml. The proposed methods were applied to dosage forms containing yohimibine and/or a mixture of yohimbine and strychine. The results obtained compared favorably with those found with alternative methods.
