Evaluation of fluorescence quenching for assessing the importance of interactions between nonpolar organic pollutants and dissolved organic matter.

The assumptions behind the fluorescence quenching (FQ) method were thoroughly evaluated to assess its potential for quickly and accurately assessing the importance of hydrophobic organic contaminant-macromolecular organic carbon interactions in aquatic systems. Perylene was used as the probe molecule to avoid problems encountered with other fluorescent probes. Results from a wide range of wetland samples suggest that static quenching dominates, that other quenchers do not interfere with analyses, and that full quenching on sorption does not occur for all samples. The latter result indicates that the quantum yield of the sorbed probe must be accounted for in quantifying the magnitude of Kmoc values by FQ. Observed Kmoc values compared favorably with those measured by the solubility enhancement method. Overall, our results suggest that FQ can be used as a quick and reliable screening tool as long as precautions are taken to ensure the validity of the results.