SPECTROCHEMICAL INVESTIGATIONS IN MOLECULARLY ORGANIZED SOLVENT MEDIA- EVALUATION OF NITROMETHANE AS A SELECTIVE FLUORESCENCE QUENCHING AGENT FOR ALTERNANT PAHS DISSOLVED IN MICELLAR SOLVENT MEDIA

Applicability of the nitromethane selective quenching rule for discrim inating between alternant versus nonalternant polycyclic aromatic hydr ocarbons (PAHs) is examined for 29 representative PAH solutes dissolve d in micellar cetyltrimethylammonium bromide (CTAB) and micellar sodiu m dodecylsulfate (SDS) solvent media. Experimental results show that n itromethane quenched fluorescence emission of only the 17 alternant PA Hs in the cationic CTAB surfactant solvent media as expected. Emission intensities of nonalternant PAHs, except for the few exceptions noted previously, were unaffected by nitromethane addition. Unexpected quen ching behavior was observed, however, in the case of nonalternant PAHs dissolved in micellar SDS solvent media. Nitromethane quenched fluore scence emission of nonalternant PAHs studied in the SDS solvent media, which is contrary to the selective quenching rule.