Oscillo-polarographic determination of boron based on its complex formation with polyphenol

Abstract

A test solution in a 50-ml measuring flask contained the following reagents, 5 ml of 1 M KCl as a supporting electrolyte, 10 ml of NH₄Cl-NH₃ buffer solution (pH 810), 05 ml of 10^-2M H₃BO₃, and (15) ml of 10^-3M of a polyphenol, such as Pyrocatechol Violet (PV), Pyrogallol Red, Bromopyrogallol Red. Difference between the oscillopolarograms of the solutions containing and not containing boric acid together with certain amounts of a polyphenol was only the variation of the peak currents based on the electrode reaction of the polyphenol, being accompanied with some variation in their peak currents with time elapsed. In the case of using PV as the polyphenol, the relation between the concentration of PV and the peak current was quantitative at the peak potential of -0.69 V vs. SCE. The decrease of the peak current (Δi_p) by the addition of boric acid in various concentrations was measured. To this procedure, the concentration ratio of PV to boric acid must be considered, too. Results obtained under various experimental conditions showed that an indirect determination of boron by oscillographic polarographic method is very promising.