Atropine Methobromide

cf. Pifer and Wollish, C.A. 46, 4952f.Solutions of the salts in acetous (anhydrous HOAc) Hg(AcO)₂ (I) are titrated with HClO₄ in anhydrous AcOH.Solution of an amount of alkaloidal halide equivalent to about 10 ml. of 0.1 N solution in 10 ml. of approx. 0.2 N Hg(AcO)₂ converts about 50% of the Hg to HgX₂.Dissolve the sample in 2-5 ml. of AcOH and 10 ml. of I, add 2 drops of 0.5% blue BZL (Ciba, Basle, CIBA 22062S) in AcOH and titrate with 0.1 N HClO₄ in AcOH containing less than 0.05% H₂O to a change from blue to red.When the color change is not sharp, e.g. precipitation with morphine, titrate to an intermediate reddish violet.Results between 98.7 and 100.3% are obtained for the HCl salts of ethylmorphine, cocaine, ephedrine, morphine, narcotine, dihydrohydroxycodeinone, papaverine, pilocarpine, and pyridoxine; and atropine methobromide, carbachol, and hyoscine-HBr.Diphenhydramine-HCl, terramycin-HCl, and tubocurarine Cl^- were determined with 0.01 H HClO₄ by using a "neutralized" Hg(AcO)₂ reagent prepared by addition of 10 ml. of 0.1 N Et₃N in AcOH to 100 ml. of 0.2 N Hg(AcO)₂, then addition of 5 ml. of 0.5% crystal violet and 0.1 N HClO₄ to the first change to green in the intermediate blue.Samples equivalent to not more than 10 ml. of 0.01 N HClO₄ are suspended in 1 ml. of AcOH, 1 ml. of Hg(AcO)₂ reagent is added, and the solution is titrated to the first change to green.The yellow color of terramycin necessitated the addition of 2 drops of 0.05% crystal violet in AcOH and titration to the absence of red tint in the green color.Aureomycin-HCl did not dissolve on addition of 1 ml. of Hg(AcO)₂ solution and reproducible results were not obtained.