Description_x000D_ General description_x000D_ Vitamin A usually occurs in food as retinyl esters, which are the pre-formed sources of vitamin A. Retinyl acetate exists as yellow crystals and is insoluble in water. It is soluble in ethanol and oils._x000D_ Application_x000D_ Retinyl acetate has been used:_x000D_ • to study its effects on cochlear development in mice_x000D_ • as a component of an internal standard to quantify antioxidants in yolk_x000D_ • as an internal standard to determine serum retinol concentration_x000D_ Packaging_x000D_ 1, 5, 25, 100 g in glass bottle_x000D_ Biochem/physiol Actions_x000D_ Retinal, retinol and retinoic acid are the aldehyde, alcohol and acid forms of vitamin A. The retinoids exist as many geometric isomers due to the unsaturated bonds in the aliphatic chain._x000D_ Retinoids also exist as retinyl esters such as retinyl propionate, retinyl acetate and retinyl palmitate. Retinyl esters provide pools of vitamin A that are converted into retinol and other retinoids as needed. Retinyl acetate is used in a wide range of biological applications._x000D_ Physical form_x000D_ Packaged as a melt and may exist as a crystalline solid or a supercooled viscous liquid_x000D_ Analysis Note_x000D_ Activity based on HPLC comparison to USP standard.