Determination of the content of vitamin D is a rather difficult problem. In the present study, we have compared methods that are most widely used for determining group D vitains. In recent years, physical and chemical methods of analysis have found increasing use due to their simplicity, sensitivity, and information value. Various methods of quality control are currently used but the future in the analysis of calciferols undoubtedly belongs to HPLC. This method is capable of simultaneously solving all problems encountered in the analysis of group D vitamins.
The idea of using a chromatographic adsorbent in the form of a thin layer fixed on an inert rigid support seems to have been suggested by Izmailov and Shraiber in 1938. Meinhard and Hall[1] in 1949 developed this notion of an ‘open column’, and in 1951 Kirchner, Miller, and Keller[2] reported the separation of terpenes on a ‘chromatostrip’, prepared by coating a small glass strip with an adsorbent mixed with starch or plaster of Paris, which acted as a binder. The strips were handled in the same way that paper is handled in paper chromatography, and indeed the original object of the thin-layer technique was to apply the methods of paper partition chromatography to an adsorption system.
Berzelius failed to make use of Faraday's electrochemical laws in his laborious determination of equivalent weights.