Differential-pulse polarographic determination of isonicotinic acid hydrazide, and analogous hydrazides in admixture

Abstract

The differential pulse polarographic behaviour of isonicotinic, nicotinic and picolinic acid hydrazides in Britton-Robinson buffers of pH 2–11 is described. The isonicotinic compound (isoniazid) is best determined at pH 5–6 at a peak potential at ca. −1.0 V (vs. Ag/AgCl). This method was applied to analysis of tablets. At pH 9, the peak potentials are −1.22, −1.34 and −1.6 V, respectively, for the three hydrazides mentioned. Calibration graphs are linear in the range 10 −6−5×10 −4 M with relative standard deviations of 1.4–2.5%.