Patent ID: 7585333

Claim:
A fluorescent whitening agent, which comprises a mixture of compounds of the formulae in which R 1 and R 2 are different and are not derived from the same amino acid or amino acid amide residue R 1 is —NH 2 , —NHC 1 -C 4 alkyl, —N(C 1 -C 4 alkyl) 2 , —NHC 2 -C 4 hydroxyalkyl, —N(C 2 -C 4 hydroxyalkyl) 2 , —N(C 1 -C 4 alkyl)(C 2 -C 4 hydroxyalkyl), a morpholino residue or an amino acid or an amino acid amide residue from which a hydrogen atom has been removed from the amino group, R 2 is an amino acid or an amino acid amide residue from which a hydrogen atom has been removed from the amino group, each of the rings designated as A represent a 5- or 6-membered saturated heterocycle, which may contain one further heteroatom and M represents hydrogen, an alkali metal atom, ammonium or a cation formed from an amine.