(2,2'-Biquinoline)-4,4'-dicarboxylic acid 1245-13-2 2,2'-Bicinchonic acid 2,2'-Bicinchoninic acid 2,2'-Dicinchoninic acid 4,4'-Dicarboxy-2,2'-biquinoline Bicinchoninic acid EINECS 214-990-9 NSC 133815