Ⅱ.Determination of weak acidic organic drugs by non-aqueous catalytic thermometric titration

Twenty weak acidic organic drugs (eleven sulfanilamide derivatives and nine other weak acidic drugs)were determined with 0.1 N tetra-n-butylammonium hydroxide and sodium methoxide. Strong base catalyzing acrylonitrile anionic polymerization was used to indicate the end-point of titration. Hydrochlothiazide and fluorouracil in tablets were determined by direct titration without extraction and separation. Satisfactory results Of the titration were obtained with a Twin—stirrer thermo— metric recorder. The emphasis of this paper is placed on selecting titrants, solvents and ther— mometric indicators in order to obtain the good titration curves, in which the end-point may be directly located by observing inflection of the curves.