1 BIH Naphthalene-2,6-disulfonic acid 1.000 2 21D Naphthalene-1,5-disulfonic acid 0.800 3 N2M 5-amino-naphtalene-2-monosulfonate 0.737 4 VBV [1,1'-biphenyl]-4,4'-disulfonic acid 0.727 5 VWO 6-azanyl-4-oxidanyl-naphthalene-2-sulfonic acid 0.700