The antimony trichloride colour test and the ultra-violet absorption of liver oils and concentrates

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Abstract
Liver oils contain 2 chromogens which, with SbCl3, give colored substances with absorption maxima at 606 m[mu] and 572 m[mu] respectively. In concentrates these maxima are displaced to 620 m[mu] and 583 m[mu]. A comparison of ultra-violet absorption spectra with spectroscopic data on the color test discloses (1) that the parallelism between the intensity of the 606 m[mu] band and the intensity of the 328 m[mu] band breaks down so seriously in extreme cases as to render it improbable that the 606 mp chromogen is vitamin A; (2) that the 572 m[mu] chromogen and the substance responsible for the 328 m[mu]. band are probably identical; (3) that the blue color for rich oils and concentrates is often much deeper than would be expected on the basis of correlation between blue color and ultraviolet absorption. Hence it is concluded that the matching of blue colors with Lovibond glasses, though it may act as a rough guide to vitamin A potency, is theoretically unsound.