EXAMINATION OF THE NITROMETHANE SELECTIVE QUENCHING RULE IN MICELLAR ANIONIC SODIUM DODECYLBENZENESULFONATE AND MICELLAR CATIONIC DODECYLETHYLDIMETHYLAMMONIUM BROMIDE SOLVENT MEDIA

Applicability of the nitromethane selective quenching rule for discrim inating between alternant versus nonalternant polycyclic aromatic hydr ocarbons (PHAs) is examined for 38 representative PAH solutes dissolve d in micellar sodium dodecylbenzenesulfonate (SDBS) and in micellar do decylethyldimethylammonium bromide (DEDAB) solvent media, Experimental results show that nitromethane quenched fluorescence of only the 20 a lternant PAHs in the cationic DEDAB surfactant solvent media as expect ed. Emission intensities of nonalternant PAHs, except for the few bord erline cases noted in previous work, were unaffected by nitromethane a ddition. Unexpected quenching behavior was observed, however, in the c ase of nonalternant PAHs dissolved in micellar sodium dodecylbenzenesu lfonate solvent media. Nitromethane quenched fluorescence emission of all 18 nonalternant PAHs studied in the SDBS solvent media, which is c ontrary to the selective quenching rule.