Ligand-exchange chromatography of alkaloids

Quantitative analysis of d-tubocurarine chloride in curare by column liquid chromatography

An improved quantitative analysis of d-tubocurarine chloride in the plant extract curare is presented. Gradient high-performance liquid chromatography on a hydrophobic stationary phase was found to be very suitable for the analysis of quaternary ammonium bases such as the complex mixture of curare alkaloids. Owing to the residual free silanol groups on the modified silica surface, the curare alkaloids are eluted from a reversed-phase column only if an electrolyte is added to the mobile phase. In order to optimize the separation, the effects of pH, the nature of the cation in the buffer and the concentration of the buffer of the retention of the alkaloids were investigated. Using a tetramethylammonium phosphate buffer at pH 4 in a gradient of water-methanol, undesirable retardation effects on the reversed-phase column could be suppressed sufficiently. As a result, an accurate method for the determination of d-tubocurarine chloride in curare was obtained. The coefficient of variation of this analysis is only 1.3%.

Chromatographic behaviour of alkaloids on thin layers of anion and cation exhangers. I. AG 1-X4 and cellex D

The chromatographic behaviour of 48 alkaloids has been studied on Bio-Rad AG 1-X4, Cellex D and microcrystalline cellulose, eluting with solutions of different pH but constant ionic strength (0.5). Many interesting separations were effected on both AG 1-X4 and Cellex D layers. The influence of pH on the chromatographic behaviour of alkaloids has been quantitatively studied and an equation was used that expresses the behaviour of the alkaloids on both AG 1-X4 (AcO-) and microcrystalling cellulose layers. The nonapplicability of this equation to Cellex D layers is discussed.