SIMULTANEOUS DIFFERENTIAL DETERMINATION O F MIXED INORGANIC ACID BY NONAQUEOUS CONDUCTOMETRIC TITRATION WITH SODIUM-BOROHYDRIDE

This study involved the simultaneous differential determination of mix ed inorganic acid by nonaqueous conductometric titration with sodium b orohydride dissolved in N,N-dimethylformamide (DMF). Inflection points were found on conductometric titration curves of mixed inorganic acid in DMF, which were caused by a difference in the acidity or reactivit y. The acid concentration of each of mixed inorganic acid was successf ully determined simultaneously by the present method. Although the rea ction of inorganic acids with sodium borohydride in DMF is generally t hought to be the competing reaction of the neutralization and redox re action, neutralization can only be followed by conductometric titratio n. An attempt was made to identify the ions in the DMF solution and th e resulting precipitates during the course of the titration by fast at om bombardment mass spectrometry (FAB-MS) and Fourier transform infrar ed spectroscopy (FT-IR). The presence of up to 5% water in the sample solution did not interfered with the present titration method. The det ermination limit was about 0.01 M by this method.