Enhancement effect on the chemiluminescence of acridinium esters under neutral conditions

Enhancement effect on the chemiluminescence of acridinium ester derivatives under neutral conditions was investigated. Additions of phenols did not enhance the chemiluminescence intensities of acridinium ester derivatives in the presence of horseradish peroxidase and hydrogen peroxide. Additions of cetyltrimethylammonium bromide apparently enhanced the chemiluminescence intensities of phenyl 10-methyl-10λ⁴-acridine-9-carboxylate derivatives with electron-withdrawing groups at the 4-position of the phenyl group. In particular, the chemiluminescence intensity of 4-(trifluoromethyl)phenyl 10-methyl-10λ⁴-acridine-9-carboxylate trifluoromethanesulfonate salt was 5.5 times stronger in the presence of cetyltrimethylammonium bromide than in its absence at pH 7. The chemiluminescence intensity of 3,4-dicyano-phenyl 10-methyl-10λ⁴-acridine-9-carboxylate trifluoromethanesulfonate salt was 46 times stronger in the presence of cetyltrimethylammonium bromide at pH 7 than in its absence at pH 10.