Sum of volatile matter at 135 °C (275 °F) and chlorides and sulfates (calculated as sodium salts), not more than 18 percent.
Water-insoluble matter, not more than 0.3 percent.
4-Amino-5-hydroxy-2,7-naphthalenedisulfonic acid, disodium salt, not more than 0.3 percent.
4,5-Dihydroxy-3-(phenylazo)-2,7-naphthalenedisulfonic acid, disodium salt, not more than 3.0 percent.
Aniline, not more than 25 parts per million.
4-Aminoazobenzene, not more than 100 parts per billion.
1,3-Diphenyltriazene, not more than 125 parts per billion.
4-Aminobiphenyl, not more than 275 parts per billion.
Azobenzene, not more than 1 part per million.
Benzidine, not more than 20 parts per billion.
Lead (as Pb), not more than 20 parts per million.
Arsenic (as As), not more than 3 parts per million.
Mercury (as Hg), not more than 1 part per million.
Total color, not less than 82 percent.
21 C.F.R. §74.1333