A review on photometric methods for the quantitation of vitamin A

The importance of fat-soluble vitamin A in the body is well known and recognized. Vitamin A is the term used for a group of fat-soluble nutrients, such as retinal, retinol, and retinyl esters. Vitamin A is essential for the human body, for example, for the proper functioning of eyesight and immunity. However, an excess or deficiency of vitamin A in the body can cause various diseases. Several methods have been described for the quantification of vitamin A in various samples, such as drugs, foods, fruits, etc. In general, to quantify vitamin A, the sample is saponified and then extracted into non-polar solvents. After the reaction of the enol form of vitamin A with chromogenic reagent, vitamin A is determined based on the absorbance of the resulting colored complex. The spectrophotometric methods are still attractive because they are easy to handle, cost-effective, and sensitive.