Studies on the Analysis of Alkaloidal Extract Preparations——Ⅱ.Determination of Nux Vomica Preparations by Thin-layer Chromatography-catalytic Polarographic Method

A thin-layer chromatographic method is proposed for separation of strychnine and brucine in the Nux Vomica preparations such as extract, liquid extract, and tincture of Nux Vomica. Good separation is obtained with alumina layer (particle size of 200 mesh, thickness 200μ) by using benzene-ethyl acetate (1:2) as solvent. After the chromatogram is developed, the spot of strychnine is collected with collecting tube and eluted with ethanol followed by catalytic polarographic determination in the base solution containing McIlvaine buffer and 0.1 M KI. The analytical method employed is based on the linear relationship of concentration of strychnine with catalytic polarograhic current. The concentration of strychnine is in the range of 3×10^-5—1.2×10^-4M. The method has the advantage of being simpler and more rapid than the extraction procedure and gives results close to the pharmacopeiacal methods. It can be applied to simultaneous determination of strychnine and brucine in the Nux Vomica preparations.