New approach to the determination of vitamin a in pharmaceutical products

A modified analytical procedure for the determination of vitamin A in pharmaceutical preparations and its method of calculation based on geometric and trigonometric relationships is presented. Ether and isopropyl alcohol solvents are replaced by hexane, a more selective solvent, for the extraction of the unsaponifiable fraction. Absorbance readings of this latter are measured at one wavelength (325 mμ) before and after the destruction of vitamin A. A comparison study of the accuracy and precision of the U. S. P. XV method and of this proposed method was made on five characteristic polyvitamin preparations and on a cod liver oil sample. Statistical analysis of the results in per cent recovery of added vitamin A has shown a 100 per cent yield by the “hexane-destruction” method, and 82 to 96 per cent yield by the U. S. P. XV method. With this proposed method, the standard deviations were less than one-third as grdeat.