Retinol chemical determination

The chemical structure of retinol was determined in 1931 by Swiss chemist Paul Karrer (1889-1971), and the compound... 

In this introduction, we do not provide a more detailed review of the classical discoveries in the field of vitamin A research. As already discussed in part, these classical discoveries included the original description of fat-soluble A and the introduction of the term ""vitamin A the recognition of retinol as a substance distinct from its carotenoid precursors the development of quantitative chemical methods for the analysis and assay of retinol and related substances the elucidation of the chemical structure and then the total synthesis of retinol, retinyl esters, and retinoic acid the description of the unique pathology of both hypovitaminosis A and h q)ervitaminosis A in experimental animals and man the elucidation of the fundamental role of retinaldehyde in vision the determination of human and animal needs for retinol or its precursors for adequate nutrition and the development of practical syntheses for the commercial production of retinyl esters to meet those nutritional needs. This historical story has been... 

Before pure vitamin A was available for chemical analysis, the vitamin A content of foods was determined by biological assays, and the results expressed in standardized international units (iu) 1 iu = 0.3 fig retinol, or 1 fig of retinol = 3.33 iu. Although obsolete, international units are sometimes still used in food labelling. 

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