BULLETIN 1390, U. S. DEPARTMENT OF AGKICULTTJRE 
Table 3. — Specifications for brilliant blue FCF 
Component 
Maxi- 
mum tol- 
erance 
(ratio 
to pure 
coal-tar 
dye) 
| 
ance S1S 
Component 
Maxi- 
mum tol- 
erance 
(ratio 
to pure 
coal-tar 
dye) 
Min- 
imum 
toler- 
ance 
Method 
ofanal- 
ysis 1 
Moisture 
Insoluble matter: 
Total 
Per cent 
10.0 
.3 
.2 
3.0 
P.ct. 
Page 
15 
1- 
16 
16-18 
19 
( 2 ) 
19 
20 
Per cent 
Aluminum 0.1 
Iron .3 
Arsenic as AS2O3 .00014 
Ether extractives: 
P.ct. 
77." 4" 
Page 
21 
21 
21-24 
Neutral 
( 3 ) 
(3} 
24,25 
1.0 - 
Alkaline ... 
24, 25 
3.0 
( 3 ) 
(«) 
None. 
.3 
.3 
Acid (3) 
Total ! .4 
Sulphur in color ; (<) 
Color aid. 
24, 25 
24, 25 
25,26 
26-28 
:::::: 
21 
Pure coal-tar dve. 
82.0 
26-28 
Subsidiary dyes.. 5.0 
( 2 ) 
1 Given in IT.. S. Dept. Agr. Bui. 1390 (rev.) (2), as for light green SF yellowish. 
2 Special method. 
3 Although no limit is defined here, a statement of the percentage found by analysis should be incor- 
porated in the foundation and supplemental affidavits. 
4 Theoretical. 
SPECIAL ANALYTICAL METHODS 
SODIUM ACETATE 
For brilliant blue FCF. — Weigh 10 grams of the dye into a 200 c. c. 
Kjeldahl flask, add 25 c. c. of water, and connect the flask in an upright 
position to a vertical straight-tube water-jacketed condenser. Insert 
a separatory or dropping funnel through the stopper of the flask, 
together with the tube leading from the flask to the condenser. Add 
15 c. c. of phosphoric acid (specific gravity 1.7) and heat the contents 
of the flask to boiling. Collect the acetic acid and condensed steam 
in a 300 c. c. Erlenmeyer flask to which has been added a standard 
solution of sodium hydroxide. Continue the boiling until about 
250 c. c. has been distilled over, replacing the distillate by water from 
the dropping funnel so that the volume in the Kjeldahl flask remains 
about 20 c. c. This distillation should require about two hours. 
At the end of the distillation period, remove the receiver and titrate 
the excess alkali with standard acid, using phenolphthalein as indi- 
cator. Run a blank distillation and deduct the resulting acidity 
found. From the corrected acidity calculate the quantity of sodium 
acetate present in the dye. 
LOWER SULPHONATED DYES 
For ponceau SX and sunset yellow FCF. — To such a volume of a 
1 per cent solution as contains 0.2 gram of dye, add 1 c c. of concen- 
trated hydrochloric acid and dilute to a volume of 50 c. c. Extract 
the lower sulphonated dyes by shaking the solution successively in 
three separatory funnels, each containing 50 c. c. of amyl alcohol. 
Wash the amyl alcohol extracts successively with 50 c. c. portions 
-of 5 per cent salt solution until the washings are colorless. Dilute 
the amyl alcohol in each funnel with 100 c. c. portions of gasoline 
{specific gravity 0.65) and remove the lower sulphonated dyes by 
washing with several 10 c. c. portions of water. Determine the 
quantity of dye colorimetrieally by comparison with a standard 
solution of the dye. 
