A search of the literature reveals very few investigations in which n-butyl phosphate is suggested for use as a solvent in electrochemical studies. This is surprising in view of its Wide acceptance as an extraction solvent. The two earliest studies were ainled at the isolation and determination of uranium. In x956 FISHER AND THOMASON 1 , realizing the problems generally associated with solvents of low dielectric constant, diluted their uranium extracts with high-dielectric solvents in order to obtain satisfactory polarographic results. In their paper they referred to some earlier, classified work done by LESTRANGE 6l al. Β°, who with n-butyl phosphate as an extraction agent, carried out a polarographic study on uranium which had been isolated from solutions which were either 5 N in nitric acid or high in aluminum nitrate content. SPLITT-GERBER a attempted to use **-butyl phosphate as a polarographic solvent but lie reported no success until dilutions were made with N-methylaceta-mide. A brief preliminary study of polarography in n-butyl phosphate was recently described 'i.
The exploratory work described herein includes an examination of the voltammetric behavior of several inorganic depolarizers, plots of the dependence of limiting currents on concentrations, and values of half-wave potentials of a large number of ions. The solvent used was lOO% n-butyl phosphate. Potentiostatic control of the working electrode was maintained at all times. Conventional d.c., filtered d.c., and first derivative d.c. polarographic techniques were utilized in the study.
EXPERIMENTAL
Apparatus
Conventional and first derivative polorograms were obtained with the Oak Ridge National Laboratory Q-I988ES voltammeter (Indiana Instrument & Chemical Corporation, Bloomington, Ind.). This was modified by the addition of a voltage follower circuita between the reference electrode of the cell and the reference electrode input of the voltammeter. The follower (Fig. I) was made from a George A. Philbriek P2A operational amplifier and powered by a Philbrick PR-3o regulated power supply. This modification was necessary because of the wave distortion resulting from the