Studies on Kitol. II. Influence of Kitol Fraction on theDetermination of the International Unit of Vitamin A.
Tadashi Tawara and Ryusuke Fukazawa
In the previous paper*, the authors showed that the unsaponifiable

matter of whale liver oil gave only the apparent absorption maxin:ium dueto the presence of a mixture of two or more substances while that oftunny liver oil gave an absorption maximum at around 328 mp. TheVitamin A fraction (fraction B) of whale liver oil gives a maximum ataround 328 mp but due to the presence of kitol fraction (fraction A), thewhale liver oil gives a very complicated absorption. Accordingly, thedetermination of Vitamin A of whale liver o:l by a spectrophotometer does
not give the correct extinction coefficient at 328 mp, only that of an apparent value, so that determination of true Vitamin A content cannot bemade by this method. This fact is borne out by the fact that with whale
liver oil, results of animal test and spectrum analysis do not coincide.'
The authors examined the influence of kitol fraction on Vitamin A by
the use of fractions A and B separated by the authors. However, this is
an intermediate report and further detailed experiments must follow since
there is no direct proof that the kitol fraction obtained does not containeven a minute amount of Vitamin A, or that it does not contain otherunsaponifiable matter.
39 g. of Vitamin A fraction and 14 g. of kitol fraction were obtained
from 53.5 g. of unsaponifiable matter of the whale liver oil. First, theinternational, unit· of Vitamin A was determined with Vitamin A fraction
and then the extinction C_?efficient at 328 mp of a mixture of 14 parts kitol
fraction to 39 parts Vitamin A fraction, which the international unit ofVitamin A was calculated. As a result, it was shown that the value ofthe international unit of Vitamin A in this case came out 12.1% higher
1than the true value of Vitamin A content. In other words, the true eontent of Vitamin A is the value obtained by subtracting 12.1% from thevalue obtained by spectrophotometric determination.
It follows, naturally, that the determined value of Vitamin A comes* Cf. Report I, p.. 85 of ·this Bulletin.

90Tadashi Tawara and Ryusuke Fukazawa

out larger than the true content of Vitamin A when the amount of kitol
content becomes large compared to the amount of Vitamin A. This willshow that a presence of kitol has a very great effect on the assay ofVitamin A by the spectrophotometer and therefore, points to the fact thatthe method of Vitamin A determination of whale liver oil must beimproved.
The authors' thanks are due to Taiyo Fisheries Co., for their kindness
in furnishing the material for these experiments.
EXPERIMENTAL
53.5 g unsaponifiable matter were obtained from 250 g. of the liver oilof a fin whale by the method as described in the previous report. From
this unsaponifiable matter, 39 g Vitamin A fraction (fraction B) and 14 g.
kitol fraction (fraction A) were obtained (loss of 0.5 g.).
1) Carl Zeiss' spectrophotometer was used to determine the international
unit of Vitamin A fraction (solvent-absolute alcohol).
1% 328m 11=454.5·B fraction-E 1cm,.
therefore, this substance contains 727,000 I. U. of Vitamin A per 1 g.
2) Kitol fraction (fraction A)-E 11cm% 290 mp=500
E 1lcm% 328mr1i=108.7
therefore, this substance would look as though it containnd 174,000 I. U. ofVit~min A per 1 g., but the Carr-Price reaction gives a red coloration andcontains virtually no Vitamin A.
3) International unit was determined with a mixtue of 39 parts Vitamin
A· fraction and 14 part kitol fraction (a pr0portion so arrived because theunspo11i:Wible matter of this whale liver oil contained these 2 fractions in
a proportion of 39 : 14). E11cm% 328mp=375·therefore, this substance must contain 600,000 I. U. of Vitamin A.
However, 1 g. of this substance contains only 39~ 14 g. of Vitamin A
fraction and, taking that the kitol fraction does not contain any Vitamin A(by Carr-Price reaction), the true content of Vitamin A can be shown by
the following equation :727,000 I. U. x -~~ · .535,000 I. U.
therefore 600,000-535,000=65,000 I. U.
Actually, 65,000 I. U. Vitamin A had been shown than was actually con-

The Influence of Kitol Fraction on the Determination of the International Unit of Vitamin A 91

tained, or in other words 12.1% more Vitamin A.
4) The determination of internatio~al unit was mad~ with a mixture ofan equal portin of A and kitol fraction which gave :1.% 328 mµ=35.8
E.lcm
therefore,. this substance seems to contain 572,800 I. U. Vitamin A but
according to the aforementioned calculations, it actually contains only
363,500 I. U. In this case, the spectrophotometric value gave 30.4% higher
content of Vitamin A than was actually present.
5) International unit was determined with the unsaponifiable matter oftunny liver oil which gave :E1lcm.% 328 mµ= 38.5
therefore, 1 g. of this substance contains 61,600 I. U. of Vitamin A.
6) International unit was determined with a mixture of 39 parts unsaponifiable matter of tunny liver oil and 14 parts kitol fraction· which gave :E1.% 328 mµ= 50.0
lcm
therefore lg. of this substance seems to contain 80,000 I. U. of Vitamin A
but according to the above calculation, the real content of Vitamin A is
45,100 I. U. In this case, ea. 77.4,o/o higher value than the actual contentof Vitamin A was obtained by the spectrophotometric determination.
7) International unit was determined of an equal amount of unsaponifiable
matter of tunny liver oil and kitol fraction which gave :E 1.% 328 mµ=·59.0lcm
therefore 1 g. of this substance shows a Vitamin A content of 94,400 I. U.
but, according to foregoing calculation, the actual content of Vitamin A
would be 30,800 I. U., if there is no presence of Vitamin A in kitol fraction.
In this case, the photometric determination has given 206.5% higher value
than the true content of Vitamin A.

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