Potentiometric determination of arsenic by potassium permanganate in alkaline solutions

The oxidation of trivalent arsenic by potassium permanganate in alkaline solutions has been studied potentiometrically. The end points are largely affected by the concentration of the reactants and the alkalinity of the reaction medium. It is found that, provided the proper alkalinity is chosen, good results could be obtained. At alkalinities as low as 0.1 N NaOH, dilute solutions could be titrated, so that the method can be applied for the determination of micro-quantities of arsenic.