Sum of volatile matter (at 135 °C) and halides and sulfates (calculated as sodium salts), not more than 8 percent.
Insoluble matter (alkaline solution), not more than 0.5 percent.
Phthalic acid, not more than 0.5 percent.
2-[3',5'-Diiodo-2',4'-dihydroxybenzoyl] benzoic acid, not more than 0.5 percent.
Fluorescein, not more than 1 percent.
4'-Iodofluorescein, not more than 3 percent.
2',4'-Diiodofluorescein and 2',5'-diiodofluorescein, not more than 2 percent.
2',4',5'-Triiodofluorescein, not more than 35 percent.
2',4',5',7'-Tetraiodofluorescein, not more than 10 percent.
4',5'-Diiodofluorescein, not less than 60 percent and not more than 95 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 92 percent.
21 C.F.R. §74.1260