Quantitative determination of drugs by means of densitometry of thin-layer chromatograms. Part 4: Determination of vitamins A and E in pharmaceutical preparations.

A quantitative method for the determination of vitamins A and E is proposed based on the direct densitometry of thinlayer chromatographic spots. An appropriate solvent system for the chromatographic separation of the vitamins and the conditions under which a linear relationship between the absorbed light and the logarithm of concentration exists (1--10 mug range) are found. The precision of the method is evaluated by a statistical treatment of the results. Satisfactory reproducibility is established-- the variation coefficient for the determination of the two vitamins is about 4--5%. The method is applied for the analysis of oil and aqueous injection solutions, mixtures containing the three vitamins A, E and D2 and some pharmaceutical preparations (Pharmavit¿ and Devitforte¿). The presence of the decomposition products and other substances (other pharmaceuticals, stabilizers, solubilizers etc.) does not affect the determination. The analysis is performed without preliminary treatment of the sample.