Table 5.

R-groups within a series of fluorescein derivatives not approved for use in humans.

Name	R2	R5	R6	R8=R13	R9	R10=R11	R12
fluorescein	H	H	H	H	O	H	OH
fluorescein butyl ester	(CH2)3CH3	H	H	H	O	H	OH
fluorescein butyl ether	H	H	H	H	O	H	O(CH2)3CH3
anthofluorescein	H	H	H	H	O	H	C6H4OH
Zinpyr-1	H	H	H	Cl	O	bipyridyl	OH