appearance dark green to black powder
infrared spectrum conforms to structure.
uv-visible spectrum C = 0.005 G/L IN ACIDIFIED 50% ETHANOL
E(541 +/- 3 NM) = 23,000 (MINIMUM)
E(274 +/- 3 NM) = 26,000 (MINIMUM)
biological stain passes staining tests
dye content ≥50.0%
solubility 1 mg/ml H2O; red to dark red or dark purple solution



