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The titration of vanadium(IV) with cerium(IV) sulphate, with nitroferroin as indicator, is proposed. Unlike ferroin, the indicator does not need a catalyst in this system. By suitable choice of experimental conditions iron(II) can be titrated first to a ferroin end-point and then vanadium(IV) to a nitroferroin end-point.

The optimum conditions for the titration of antimony(III) with dichromate, and diphenyl-aminesulphonic acid as indicator, have been established. No iodine catalyst is used; the analytical reaction is based on an induced reaction with iron(II) as inductor. The titration can be done as easily as an iron(II) titration and the end-point is equally sharp. Titrations are possible with 0.01N solutions.

A simple titrimetric procedure for the determination of iron(II), antimony(III) and arsenic-(III) in a mixture, with cerium(IV) sulphate as titrant, is proposed. The end-points can all be detected with ferroin or potentiometrically. Phosphoric acid medium is used for titration of the iron(II), then acetic acid medium for the titration of antimony(III), and finally the arsenic(III) is titrated in presence of iodine as catalyst. The procedure utilizes a single portion of test solution; it can be adopted for the analysis of binary mixtures.