The spectrophotometric determination of chromium and vanadium with ortho-dianisidine

✍ Scribed by M. Ariel; J. Manka

• Publisher: Elsevier Science
• Year: 1961
• Tongue: English
• Weight: 585 KB
• Volume: 25
• Category: Article
• ISSN: 0003-2670
• DOI: 10.1016/0003-2670(61)80154-2

✦ Synopsis

REAGENTSAND SOLUTIONS

(I) Ortho-dianisidine dihydrochloride (3,3'-dimethoxybenzidine). This is a crystalline solid, soluble in water and acids. Its reduced form is colorless, while its oxidized form is red in strongly acid solutions and green in solutions whose pH is higher than 2.1. The formal oxidation potential reaches its maximum value in solutions more acid than 6 N suifuric acid8910. For the purpose of this investigation, a 1% solution of the reagent was prepared by dissolving I g in a small quantity of water containing 2 ml of concentrated acetic acid, stirring vigorously to promote dissolution and making up to IOO ml with distilled water. This reagent solution was then transferred to a polyethylene bottle and stored in a dark place. No change in its activity could be observed within one month of its preparation.

(2) Standard chromium(V1) stock solution, containing I g of Cr+6 per liter, was prepared by dissolving 2.8283 g of dried potassium dichromate in distilled water and making up to I 1.