USA is probably the only country in the world to set up a system of issuing lot to lot certification for synthetic food, drug and cosmetic dyes, pigments & lakes.
Typically all synthetic dyes, lakes and pigments used in food, drug and cosmetic industry need the color additive to be batch to batch certified from US FDA. There is a positive list of such colorants which need compulsory certification from US FDA. This means that US FDA will analyze a sample from the batch to find if the said batch sample meets the requirements for dye content, purity and all impurities which are stated in the regulation for that color additive.
Using an uncertified form of a color additive that requires US FDA certification makes an FDA-regulated product adulterated under the US law, and FDA can take action against the product.
US FDA determines the need for batch certification based on whether the color additive needs this level of control to protect the public health. Some color additives, in their uncertified forms, might contain impurities at levels that pose a health concern.
Certified color additives generally have three-part names consisting of a group of letters (“FD&C,” “D&C,” or “Ext.D&C”), a color, and a number. An example is “FD&C Yellow No. 5.”
US FDA personnel evaluate batch sample for physical appearance and chemically analyze it for purity (total color content), moisture, residual salts, unreacted intermediates, colored impurities other than the main color (called subsidiary colors), any other specified impurities, and the heavy metals lead, arsenic, and mercury.
FDA will review the results for compliance with the identity and specifications described in the listing regulation for the color additive.
If US FDA find that the sample meets these requirements, FDA issues a certificate for the batch. The certificate identifies the color additive, the batch weight, the uses for which the color additive is certified, the name and address of the owner, and other information as required. FDA also assigns a unique lot number for the batch.