A colorimetric method for the estimation of some tropine alkaloids

The acid dye method for the estimation of certain alkaloids and other base compounds has been extended to atropine and other tropine alkaloids. This procedure is based on the observation that certain acidic dyes combine with many alkaloids to form saltlike compounds which are characterized by their solubility in organic solvents. They can thus be separated and the dye component can be estimated colorimetrically. The procedure has been adapted to the determination of atropine and hyoscyamine with the help of bromocresol purple. The method permits the quantitative estimation of these alkaloids in amounts ranging from 0.1 to 2.0mg. per sample. Applications of the method to tinctures and extracts of belladonna and hyoscyamus will be discussed.