Micro-method for estimating vitamin A by the Carr-Price reaction

Abstract

The reaction mixture (0.01-0.03 cc.) is photographed through light filters together with a series of permanent standards and the film analysed electrophotometrically. The range of utility of the method is 0.06-0.4 i.u. of the vit. A. Fading curves observed were in agreement with curves calculated on the basis of a first order reaction both for color development and for fading. If the conc. of vit. A in the blood is calculated from the maximum color obtained the error due to different fading rates will generally not be greater than 5%.