Spiro[isobenzofuran-1(3H),9'-[9H]xanthen]-3- one,4,7-dichloro-3',6'-dihydroxy-2',4',5',7'- tetraiodo-

4,7 – dichloro-fluorescein with iodine in potassium (or sodium) and the presence of copper chloride tetraiodide.

blue light red. Soluble in water for cherry red, no fluorescence. In concentrated sulfuric acid for brown light yellow, dilution after brown light red precipitation. Dye aqueous solution to join sodium hydroxide have carmine soluble precipitation

Standard	Light Fastness	Heat-resistant(℃)		water	Sodium Carbonate(5%)	Hydrochloric acid(5%)
		Melting point	Stable
ISO	General			Insoluble		Good