SPECTROSCOPIC INVESTIGATIONS IN MOLECULARLY ORGANIZED SOLVENT MEDIA -PART 5 - FLUORESCENCE BEHAVIOR OF POLYCYCLIC AROMATIC-HYDROCARBONS DISSOLVED IN CETYLPYRIDINIUM CHLORIDE PLUS ZWITTERIONIC AND CETYLTRIMETHYLAMMONIUM CHLORIDE PLUS ZWITTERIONIC MIXED SURFACTANT SYSTEMS

Applicability of the cetylpyridinium (CPy+) cation as a selective fluo rescence quenching agent for discriminating between alternant versus n onalternant polycyclic aromatic hydrocarbons (PAHs) is examined for 25 representative solutes dissolved in two aqueous micellar cetylpyridin ium chloride (CPC) + zwitterionic surfactant solvent media. Experiment al results show that the CPy+ cation effectively quenched fluorescence emission of all 10 alternant PAHs studied despite the presence of str ong intramicellar coulombic interactions. Emission intensities of the 15 nonalternant PAHs also decreased upon addition of CPC to the zwitte rionic surfactant solutions. Reduction in emission intensities for the nonalternant PAHs is rationalized in terms of changes in micellar str ucture caused by the coulombic interactions, rather than from loss of quenching selectivity by the CPy+ cation. (C) 1998 Elsevier Science B. V. All rights reserved.