Volatile matter at 135 °C (275 °F), not more than 3 percent.
Matter insoluble in N,N- dimethylformamide, not more than 1 percent.
Isatin, not more than 0.3 percent.
Anthranilic acid, not more than 0.3 percent.
Indirubin, not more than 1 percent.
Lead (as Pb), not more than 10 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 95 percent.
21 C.F.R. §74.3106