Natural monocrystalline pyrite as a sensor in non-aqueous solution Part I:Potentiometric titration of weak acids in,N,N-dimethylformamide,methylpyrrolidone and pyridine

摘要

The possibility of applying natural monocry staline pyrite as a sensor for the potentiometric titration of weak acids in N,N-dimethylformamide,methylpyrrolidone and pyridine was investigated.The potential of this electrode in N,N-dimethylformamide,methylpyrrolidone and pyridine exhibits a sub-Nernst dependence.In N,N-dimethylformamide the slope(mV/pH)is 39.0 and in methylpyrrolidone it is 45.0.The potential jumps at the titration end-point obtained in the titration of weak acids are higher than those obtained by the application of a glass electrode as the indicator electrode The potential in the course of the titration and at the titration end-point(TEP)are rapidly established.Sodium methylate,potassium hydroxide and tetrabutylammonium hydroxide(TBAH)proved to be very suitable titrating agents for these titrations.The results obtained in the determination of the investigated weak acids deviate by 0.1-0.35%with respect to those obtained by using a glass electrode as the indicator electrode.