1 F6Z 3',6'-dihydroxy-3-oxo-3h-spiro[2-benzofuran-1,9'-xanthene]-5-carboxylic acid 1.000 2 FGT 3,3-bis(4-hydroxyphenyl)-2-benzofuran-1-one 0.857 3 IOQ 2',7'-bis(chloranyl)-3',6'-bis(oxidanyl)spiro[2-benzofuran-3,9'-xanthene]-1-one 0.833 4 4CI N-[3',6'-bis(oxidanyl)-3-oxidanylidene-spiro[2-benzofuran-1,9'-xanthene]-5-yl]methanethioamide 0.806 5 F6Y 3',6'-dihydroxy-3-oxo-3h-spiro[2-benzofuran-1,9'-xanthene]-6-carboxylic acid 0.806 6 ORE 4-(2,7-difluoro-6-hydroxy-3-oxo-3h-xanthen-9-yl)isophthalic acid 0.758 7 FDS Fluorescin 0.710 8 FLU 2-(6-hydroxy-3-oxo-3h-xanthen-9-yl)-benzoic acid 0.710