Patent ID: 7491832

Claim:
A sulfonate compound represented by a formula (I) below, where an atomic group A-O is an atomic group that forms a fluorescent compound (excluding hydroxycoumarin and derivatives thereof) upon cleavage of a covalent bond with a sulfonyl group, there may be one or plural atomic groups B—SO 3 — bound to an atomic group A, A is represented by a formula (X-1) or (X-2) below, where, in the above formulae, X 1 , X 2 , X 3 and X 4 each denote a hydrogen atom or halogen atom, and may be the same or different, and an atomic group B is at least one selected from the group consisting of a pentafluorophenyl group, a 2,4,6-trifluorophenyl group, a 2,4,6-tris(trifluoromethyl)phenyl group, and a 2,4-bis(trifluoromethyl)phenyl group.