Rapid Evaluation of Effect of Excipients on Color Fading II

Synthesis, characterization and thermal behaviour of some metal indigodisulphonates

“…This dye has been used as an indicator in the titration ", 0 of antimony(V) with titanium(Ill) [1] and of iron(Ill)with chromium(ll) [2,3] in an atmosphere of carbon dioxide. Studies carried out in solution on the colour-fading of this dye have indicated that the fading is due to oxidation-reduction processes as well as to a dependency on the light intensity [4].Although the photodecomposition of indigocarmine appears to be the main cause of colour instability, the thermal decomposition of this dye in solution has been reported [4][5][6][7]. From the Arrhenius plot of the dye at pH 7.0, a half-life of 234 days at 25 ~ was reported [6].…”