The spectrophotometric determination of vanadium(V) with 3,3′-dimethylnaphthidine

Abstract

An investigation has been made of the factors concerned in the reaction of vanadium(V) with 3,3′-dimethylnaphthidine. Some probable causes of previous difficulties in the application of the reaction in spectrophotometric analysis have been elucidated. A simple procedure is given for the spectrophotometric determination of vanadium in the range from 0·08 to 2 p.p.m.; with 0·32 p.p.m. the coefficient of variation ranged from 0·60 per cent. for analyses at one time to 1·8 per cent. for analyses over a period of 3 months. Small, but significant, deviations from adherence to Beer's law occur. The limit of detection is about 0·004 p.p.m. of vanadium. The method is selective; the effects of numerous foreign ions have been examined, and interfering effects were found only with chromium(VI), iron(II), iron(III), cerium(III) and cerium(IV).