COAL-TAR FOOD DYES 
Table 2. — Specifications for sunset yellow FCF 
Component 
Maxi- 
mum tol- 
erance 
(ratio 
to pure 
coal-tar 
dye) 
Min- 
imum 
toler- 
ance 
Method 
of analy- 
sis i 
Component 
Maxi- 
mum tol- 
erance 
(ratio 
to pure 
coal-tar 
dye) 
Min- 
imum 
toler- 
ance 
Method 
of anal- 
ysis i 
Per cent 
in. o 
P.ct. 
Page 
15 
15 
16 
16.18 
Per cent 
0.1 
.00014 
( 2 ) 
( 2 ) 
( 2 ) 
2 
T 3 ) 
P.ct. 
„__„ 
82 
Page 
21 
24 
Total 
.3 
.2 
5.0 
.5 
( 2 ) 
( 3 ) 
None. 
Ether extractives: 
24,25 
Alkaline 
24,25 
19 
19 
20 
21 
21 
21 
24,25 
Total 
24, 25 
25,26 
i 26-28 
.3 
Pure coal-tar dve 
<26-2R 
.3 
.1 
Lower sulphonated dyes. 
5.0 
( 5 ) 
Aluminum 
i Given in U. S. Dept. Agr. Bui. 1390 (rev.) (*). 
2 Although no limit is defined here, a statement of the percentage found by analysis should be incor- 
porated in the foundation and supplemental affidavits. 
3 Theoretical. 
4 As for Ponceau 3R, etc. 
J Special method. 
BRILLIANT BLUE FCF 
Brilliant blue FCF, a triphenylmethane dye (CayH^OgSa^Na,), is 
the disodium salt (Fierz' Farbenchemie, 4, V- 189) of the product 
obtained by condensing benzaldelryde-o-sulphonic acid with ethyl- 
benzylaniline-sulphonic acid. As in the case of the other dyes of 
this type, pure intermediates are essential. 
The following patents pertaining to the manufacture of the am- 
monium salt of this dye have been issued: United States patent 
564801 (8); British patent 5068 (1896) ; German patents 88952 (o) and 
89397 (7); and French patent 254742 (6). A complete description 
of the ammonium salt may also be found in the Colour Index (11) 
under No. 671, alphazurine FG. 
Brilliant blue FCF is a dark purple bronzy powder which dissolves 
easily in water to form a greenish-blue solution. Addition of hydro- 
chloric acid to the aqueous solution produces a green solution which 
changes to yellow upon further addition of acid. Alkali does not 
change the color of the cold solution, but a violet color is produced 
when the solution is boiled. The dye dissolves in concentrated 
sulphuric acid, forming a yellow solution which changes to green 
when diluted with water. The dye also dissolves in 95 per cent 
alcohol. 
The methods of examination and the specifications for this dye 
are indicated in Table 3. The analytical data given here should be 
incorporated in the foundation and supplemental affidavits (12). 
