INDIGO CARMINE* C. I. FOOD BLUE 1 * FD & C BLUE 2 * INDIGOTINE * ACID BLUE 74
DEFINITION
Indigo Carmine consists essentially of a mixture of disodium 3,3' dioxo - 2,2' -bi-indolylidene-5,5' - disulfonate, and disodium 3,3' - dioxo-2,2' - bi-indolyldene-5,7' -disulfonate and subsidary colouring matters together with sodium chloride and/or sodium sulfate as the principal uncoloured components.
Indigo Carmine is described as the sodium salt. The calcium and the potassium salt are also permitted.
Content not less than 85% total colouring matters, calculated as the sodium salt;
disodium 3,3' -dioxo-2,2' -bi-indolylidene-5,7' -disulfonate : not more than 18%
DESCRIPTION
Dark - blue powder
IDENTIFICATION
a. Spectrometry
b. Orange solution in water
Maximum
in water at ca 610 nm .
Water Insoluble matter
Not more
than 0.2%
Subsidiary colouring matters
Excluding
disodium 3,3' -dioxo-2,2' -bi-indolylidene-5,7'
-disulfonate :not more than 1.0%
Organic compounds other than colouring matters
[Isatin-5-sulfonic
acid / 5-sulfoanthranilic acid / Anthranilic acid
] - Total not more than 0.5%
