Amperometric determination of chromium (III) in the presence of chromate, using ethylendiaminetetraacetic acid

Abstract

1. The formation of less inert complexes of chromium (III) with acetate or bicarbonate ions substantially accelerates the complex formation of chromium with EDTA, which permits an amperometric determination of chromium in the titration of an excess of the reagent with a solution of copper salt. TABLE 2. Determination of Chromium (III) in the Pres-ence of Chromate (n=3; α=0.95). RatioCr3+/Cr (VI) Amount of Cr3+, mg. taken found taken found taken found 1:0 1,14 1,15±0,06 1,71 1,72±0,09 3,50 3,48±0,07 1:50 1,71 1,72±0,04 2,86 2,86±0,08 3,50 3,50±0,04 1:100 1,71 1,69±0,05 2,86 2,85±0,04 3,50 3,52±0,10 2. The method permits the determination of 1–3 mg chromium (III) in 10 ml of a solution with an error of less than 1%. The determination is not hindered by hundredfold amounts of chromate.