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Physical & Chemical properties

Water solubility

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Description of key information

As the test item is instable in water a neutral pH, the water solubility of the stable oxidised form Indigo was determined. The water solubility of Indigo lies below the limit of quantification of 0.05 mg/L.
As the determination of the water solubility of indigo vat potassium salt according to guidelines is not possible, the maximum solubility of the leuco-indigo potassium salt in the aqueous potassium hydroxide solution was calculated from the formulation at its maximum possible leuco-indigo concentration.
The approximate solubility of Vat Indigo Potassium Salt in an aqueous alkaline solution is 400 g/L.

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Additional information

The test substance is synthesized and handled as an 15% to 50% aqueous potassium hydroxide solution (pH 13) only under inert gas atmosphere. It is instable in an aqueous phase at neutral pH or as solid material on air and oxidises rapidly to indigo CAS 482-89-3. The determination of the water solubility of indigo vat potassium salt according to guidelines is hence not possible. The maximum solubility of the leuco-indigo potassium salt in the aqueous potassium hydroxide solution was calculated from the formulation at its maximum possible leuco-indigo concentration.

The approximate solubility of Vat Indigo Potassium Salt in an aqueous alkaline solution is 400 g/L.

The water solubility of indigo lies below the limit of quantification of 0.05 mg/L