Voltammetric determination of betulinic acid at lead film electrode after chromatographic separation in plant material

The construction and application of a novel electrochemical detection system with an in situ plated lead film electrode for high-performance liquid chromatography (HPLC) is described. The working electrode of interest was tested as a potential sensor for the adsorptive stripping voltammetric determination of betulinic acid (BA). The high sensitivity of the proposed electrochemical detection results from the accumulation by adsorption of BA on the lead film surface before the proper electrode process. In a solution of sodium hydroxide, used as a supporting electrolyte for the proposed voltammetric method, the oxidation signal for BA was found to be proportional to the BA concentration in the range from 0.02 to 0.5 μg L−1 with a limit of detection equal to 0.009 μg L−1 (with preconcentration for 15 s). The voltammetric detection was successfully applied to the determination of BA in the birch bark (Betula verrucosa) extracts after HPLC separation. The content of BA obtained by the proposed method was in close agreement with that obtained by HPLC coupled with photodiode array detector (HPLC–PAD). This appears to be the first application of electrochemical detection to the determination of pentacyclic triterpene.