Polarographic Studies on Sarkomycin

Abstract

Nicotinic acid hydrazid (NH) gave three waves at the dropping mercury electrode and can be polarographically determined. Sarkomycin nicotinic acid hydrazid derivative (SK-NH), consisting of sarkomycin (SK) and NH, gave three polarographic waves, one of which disappeared in alkaline pH region. The half-wave potential of the second wave of SK-NH was the same as that of the first wave of SK and the half-wave potential of the third wave in the acid pH region was the same as that of the second wave of NH. The relation between limiting current and concentration of SK-NH was linear, but the regression obtained by one lot of sample was different from that by another lot of sample. The regression of limiting current of the third wave at pH 8.5 upon NH content was coincident within error throughout the samples used herein. Sarkomycin S1 gave three waves at the dropping mercury electrode. The first and the second waves were purely controlled by the reaction rate and the third wave controlled by diffusion. The relation between limiting current of each wave and concentration yielded straight lines, but sometimes another line was produced, probably because of the status of the solution. At pH 10.0, S1 showed an oxidation wave and positive nitroprusside reaction and moreover, reacted with monoiodoacetic acid. The mixture of S1 and CoCl2, seemingly gave a hydrogen catalytic wave due to the SH group in ammonia buffer. Therefore, S1 exists as thiol in alkaline solution. Sarkomycin S2 gave three waves at the dropping mercury electrode. The first wave was purely controlled by the reaction rate and the others by diffusion. The relation between limiting current of each wave and concentration yielded straight lines, but values obtained in some cases did not coincide with those above. At pH 10.0, S2 showed an oxidation wave and positive nitroprusside reaction and reacted with monoiodoacetic acid. Furthermore, the mixture of S2 and CoCL in ammonia buffer seemingly gave the hydrogen catalytic wave due to the SH group. Therefore, S2 might be decomposed to thiol in alkaline solution. Sarkomycin (SK) can be polarographically estimated by treatment with sodium sulfite. The waves of SK disappeared on addition of sodium sulfite and the decreased limiting current was linearly related to SK concentration. A convenient and rapid method for the determination of sarkomycin (SK) is proposed. This method is based on the amperometric titration of SK in hydrochloric acid with potassium bromate-bromide solution, using the rotating platinum wire electrode to indicate the end-point. By application of this method such a small amount even as 0.05 unit of SK can be successfully determined.