Objective: The aim of the present study was to optimize an RP-HPLC method for determination of solasodine, a steroidal alkaloid with various pharmacologic properties, in herbal medicinal preparations. Methods: Various chromatographic parameters including the composition of mobile phase and its organic and pH modifiers, mode of elution and column temperature were investigated using analytical C18 columns as stationary phase. Acetonitrile and methanol were examined in combination with deionized water and different aqueous buffers as mobile phases. Results: A mixture of methanol:KH2PO4 buffer (pH 2.5) at the ratio of 75:25 %v/v in an isocratic elution mode produced more symmetric, sharper peaks with better retention times and capacity factor than that of acetonitrile:KH2PO4 buffer. The optimum column temperature was found at 25°C. The standard calibration curve showed a very good linearity (R2=0.9966) in the range of 1-25 μg/ml with acceptable inter-day and intra-day precisions and accuracy. In addition, the LOD and the LOQ of the method were determined at 0.2 and 0.7 μg/mL, respectively. Conclusion: This developed and validated method is simple and quite rapid and can be used for routine determination of solasodine in samples such as traditional medicinal preparations.
Key words: Solasodine, Steroidal alkaloid, RP-HPLC, Validation.