Abstract
It has been related hitherto that trivalent chromium reacts very slowly with EDTA and sexivalent chromium does not react with it.
The authors have found that, if trivalent chromium is newly prepared by reducing sexivalent chromium with a suitable reducing agent, it reacts rapidly with EDTA and subsequently forms Cr(III)-EDTA complex which shows absorption peaks at 395 mμ and 550 mμ. Consequently, reducing agents such as ascorbic acid, hydroquinone, sulfite and thiosulfate can be determined indirectly by measuring absorbance at 555mμ.
It is considered that the very slow reaction of Cr3+ with polyaminocarboxylic acids may be due to the slow rate of exchange reaction of water molecules coordinated to chromium ion, which makes it reasonable that the newly reduced trivalent chromium ion reacts rapidly with EDTA.
