JOURNAL OF AGRRETIJRAL RESEARCH 
Vol. XXVI Washington, D. C., December i, 1923 No. 9 
THE QUANTITATIVE DETERMINATION OF CAROTIN 
BY MEANS OF THE SPECTROPHOTOMETER AND 
THE COLORIMETER 1 * 
F. M. Schertz 
Biochemist in Soil Fertility Investigations , Bureau of Plant Industry , United States 
Department of Agriculture 
INTRODUCTION 
The present status of our knowledge regarding carotin, as well as the 
other chloroplast pigments, is far from satisfactory. Due to this fact 
the various methods of quantitatively determining these pigments have 
been frequently investigated. Of the four chloroplast pigments, carotin, 
xanthophyll, chlorophyll a, and chlorophyll b, carotin is perhaps the best 
known, consequently more attempts have been made to determine this 
pjgment quantitatively. In this paper, only methods which relate to 
carotin will be discussed, leaving the methods for xanthophyll and 
chlorophyll to be brought up later. Since the same principle is involved 
in quantitatively determining yellow pigments other than the carotinoids, 
the literature regarding these will be referred to briefly. 3 
In 1887 Arnaud (1) made a rough estimation of carotin by means of 
the colorimeter. This method was later used by Kohl, Willstatter and 
Stoll, Goerrig, Palmer (12), and Escher (2). 
Monteverde and Lubimenko (11) devised a spectro-colorimetric method 
for quantitatively determining carotin, xanthophyll, and the chlorophylls. 
The method consisted in comparing the unknown with a standard so 
that the absorption spectra of the two solutions were of equal intensity. 
Jacobson (5) determined the ether-soluble yellow pigments in alfalfa 
leaves by weighing the residue after saponification and evaporation of 
the solvents. This residue consisted not only of carotin but xanthophyll 
and ether-soluble impurities. 
In 1912, Wurmser and Duclaux ( 13 ) spectrophotometrically deter¬ 
mined the lipo-chrome (carotin and xanthophyll) content of Chondrus 
crispus and Rhodymenia palmata. Their measurements were made at 
X = 450 millimicrons (my) but they do not explain how the method was used. 
Mathewson (1916) (7) has shown very conclusively that the spectro¬ 
photometer may be used in the analysis of food coloring matter. He (8) 
has given a procedure for estimating small amounts of organic compounds 
by converting them into colored derivatives. In a subsequent paper (9) 
spectrophotometric data which have been applied to the quantitative 
estimation of yellow AB, yellow OB, Butter Yellow and Sudan I are given. 
Perhaps the greatest stride forward, in the matter of quantitative 
spectrophotometrical data regarding dyes has been made by Gibson, 
McNicholas, Tyndall, Frehafer, and Mathewson (3). They have given 
the data in a form which is readily available for analytical purposes. 
1 Accepted for publication October 2, 1923. 
* Reference is made by number (italic) to Literature cited, p. 400. 
Journal of Agricultural Research, 
Washington, D. C. 
aic 
U83) 
71686—24-1 
Vol. XXVI, No. 9 
Dec. 1, 1923 
Key No. G-339 
