Determination of ajmalicine in reserpine raw materials by liquid chromatography with fluorescence detection

A method is presented for determination of ajmalicine in reserpine raw materials by liquid chromatography (LC) with fluorescence detection. The sample is dissolved in a very small volume of chloroform, and the resulting solution is diluted with methanol. The reference solution of ajmalicine is prepared directly in methanol. For LC, a 30 cm long normal-phase column is used. The mobile phase is methanol containing a small volume of an aqueous solution of 1-pentanesulfonic acid, sodium salt. Detection is by fluorescence with excitation at 280 nm and emission at 360 nm. In 3 samples, the ajmalicine contents ranged from 1.2 to 1.9%.