QUENCHING OF FLUORESCENCE OF 2-ANTHRACENE SULFONATE BY CETYLPYRIDINIUM CHLORIDE IN MICELLAR SOLUTIONS OF TWEENS, TRITON X-100, SODIUM DODECYL-SULFATE (SDS) AND CETYLTRIMETHYLAMMONIUM BROMIDE (CTAB)

The results of the fluorescence quenching of 2-anthracene sulphonate by cetylpyridinium chloride in ionic and non-ionic micellar environments are presented. The static quenching process (lifetime, 4.5 ns) was exploited to estimate the bimolecular quenching rate constants and binding constants between the probe and the quencher from the Stern-Volmer equation, the aggregation number of the surfactant micelles, and the occupancy number of the quencher in the micelle and the binding constant of the quencher with the micelle from the Encinas-Lissi equation. Both ionic and non-ionic micelles, ie. cetyltrimethylammonium bromide, sodium dodecylsulphate, Triton X-100, Tween-20, Tween-40, Tween-60 and Tween-80, were employed. In the Tween series (Tween-20 to Tween-80), the micellar aggregation numbers systematically varied. The average occupancy number of the quencher in the micelle and the binding constant of the quencher with the micelle showed a linear correlation with the aggregation number of the micelles.