Sum of volatile matter (at 135 °C) and chlorides and sulfates (calculated as sodium salts), not more than 18 percent.
Water-insoluble matter, not more than 0.4 percent.
1-Hydroxy-9,10-anthracenedione, not more than 0.2 percent.
1,4-Dihydroxy-9,10-anthracenedione, not more than 0.2 percent.
p- Toluidine, not more than 0.1 percent.
p- Toluidine sulfonic acids, sodium salts, not more than 0.2 percent.
Subsidiary colors, not more than 1 percent.
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 80 percent.
21 C.F.R. §74.2602a