The use of borohydrides of alkaline metals in the volumetric analysis of medicaments.

The possibility and conditions of determination of weak acid type medicaments were examined, using aqueous and non-aqueous sodium borohydride volumetric solutions. The process and control of titration were carried out potentiometrically and visually using acido-basic indicators. It was shown that for practical applications sodium borohydride aqueous solutions are more suitable. Analytical methods of determination for medicaments from the group of sulphonamides and barbiturates and their sodium salts, for phenylbutazone and kebuzone, salicylamide, nalidixic acid and theophylline were elaborated. All results were in good agreement with methods used in CsL 3, or other alternative methods. The advantages of the proposed method are good stability of sodium borohydride volumetric solution and insensitivity of titrated systems to CO2 from the atmosphere, which is unavoidable with alkalimetric titrations in aqueous and non-aqueous systems. An hypothesis has been suggested to explain the probable reactive mechanism of determination, supported by results obtained with the proposed analytical methods using a medium of suitable organic solvents with a maximum content of ca. 15% water near the final point of titration.