“…During our programme for the development of analytical methods for important medicinal plants, we have found that the isocratic methods reported provided inaccurate results owing to the inadequate resolution of compounds which are eluted quickly, and that the quantitative determination of sennosides A and B becomes difficult in samples which contain relatively low concentrations (2-5 mg/mL) of these two compounds. Furthermore, some of the sample extraction procedures were time-consuming, and certain analyses were performed with large column diameters and with relatively high flow-rates (Ohshima and Takahashi, 1983), or at extreme pH limits of the mobile phase (Tanaka et al, 1982;Srivastava et al, 1983;Verma et al, 1996) resulting in high column backpressures during repeated analyses which could shorten the column life. This led us to develop an economically feasible HPLC method with an extraction procedure that would provide better recoveries without high column back-pressure, which would operate at moderate pH and flow-rate, and with acceptable resolution for all of the constituents present in crude extracts of C. angustifolia.…”