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

In this investigation, nitromethane, nitrobenzene, and 1,2,4-trimethox ybenzene are evaluated for their class selectivity and efficiency as f luorescence quenchers of polynuclear aromatic hydrocarbons (PAHs). Con ditional Stern-Volmer quenching constants are utilized for qualitative and quantitative evaluation at known quencher concentration and fluor escence excitation and emission wavelengths. From these measurements, nitromethane is determined to be the most selective quencher for alter nant PAHs, 1,2,4-trimethoxybenzene is somewhat less selective for nona lternant PAHs, and nitrobenzene is an effective but nonselective quenc her. The utility of this technique is demonstrated by application to a complex coal tar sample after separation of the individual PAH compon ents by microcolumn liquid chromatography.