ANNEX 2 provides general guidance on specifications for colour lakes prepared by the reaction of alumina and appropriate colouring agents.
GENERAL SPECIFICATIONS FOR ALUMINIUM LAKES OF COLOURING MATTERS | |
Prepared at the 25th JECFA (1981) and published in FNP 19 (1981) and FNP 52 (1992). | |
DEFINITION |
Aluminium lakes are prepared by reacting colouring matter complying with the purity criteria set out in the appropriate specification monograph with alumina under aqueous conditions. The alumina is usually freshly prepared undried material made by reacting aluminium sulfate or chloride with sodium carbonate or bicarbonate or ammonia. Following lake formation, the product is filtered, washed with water and dried. |
ASSAY |
Content of colouring matter shall be within the range specified by the vendor. |
IDENTIFICATION |
|
Solubility (FNP 5) |
Insoluble in water |
Identification of colouring matter (FNP 5) |
Pass test |
PURITY |
|
Water soluble chloride and sulfate calculated as sodium salts (FNP 5) |
Not more than 2% |
Hydrochloride acid insoluble matter (FNP 5) |
Not more than 0.5% |
Ether extractable matte (FNP 5) |
Not more than 0.2% (Method II) |
Arsenic (FNP 5) |
Not more than 3 mg/kg (Method II) |
Lead (FNP 5) |
Not more than 10 mg/kg |