QUANTITATIVE-EVALUATION OF SELECTIVE FLUORESCENCE QUENCHERS FOR POLYNUCLEAR AROMATIC-HYDROCARBONS

In this investigation, nitromethane, nitrobenzene, and 1,2,4-trimethoxybenzene are evaluated for their class selectivity and efficiency as fluorescence quenchers of polynuclear aromatic hydrocarbons (PAHs). Conditional Stern-Volmer quenching constants are utilized for qualitative and quantitative evaluation at known quencher concentration and fluorescence excitation and emission wavelengths. From these measurements, nitromethane is determined to be the most selective quencher for alternant PAHs, 1,2,4-trimethoxybenzene is somewhat less selective for nonalternant PAHs, and nitrobenzene is an effective but nonselective quencher. The utility of this technique is demonstrated by application to a complex coal tar sample after separation of the individual PAH components by microcolumn liquid chromatography.