Purify iodinin through a column of silica gel and elute with Me2CO/CHCl3, then recrystallise it from CHCl3 to give purple crystals with a copper-coloured luster. [Clemo & Dalgleish J Chem Soc 1481 1950, Gerber & Lechevalier Biochemistry 3 598 1964, Beilstein 23 III/IV 3227,]
