CORRECTION OF FLUORESCENCE INNER FILTER EFFECTS AND THE PARTITIONING OF PYRENE TO DISSOLVED ORGANIC-CARBON

The ability of dissolved organic carbon (DOG) to bind pyrene can be mo nitored by fluorescence quenching. Inner filter effects, caused by DOG , complicate the interpretation of the partitioning coefficient of DOC to pyrene. Since DOC absorbs and fluoresces at the excitation wavelen gth of pyrene, by fitting the DOC self-quenching curve to a simple emp irical model that quantifies the absorbance in the spectrofluorimeter' s interrogation zone, one can obtain the necessary information to corr ect for the inner filter effects. This model can be combined with the Stern-Volmer equation to give a single equation that models the total fluorescence of a quenching experiment, and from which a value for the linear Stern-Volmer quenching constant, corrected for the inner filte r effects, may be obtained. The mechanisms of inner filter effects are discussed and then quantified, leading to a mathematical model of a s elf-quenching curve. This is then reduced to the empirical model of DO C self-quenching.