CORRECTION OF POLYCHROMATIC LUMINESCENCE SIGNALS FOR INNER-FILTER EFFECTS

Fluorescence (FL) and absorbance (ABS) data are acquired simulataneously with a multiple detector spectrometer. The measured ABS is utilized in mathematical equations for automatic correction of fluorescence signals for attenuation (inner-filter effects) caused by significant absorption of the excitation or emission radiation by the fluorophore or other species. Correction equations are presented which apply to situations in which the excitation or emission beam cannot be considered monochromatic, for collection geometries involving optical fibers, and for chemiluminescence measurements. The correction scheme was tested with quinine sulfate (QS) as the analyte in the absence and presence of other chromophores (gentistic acid and methyl red). These corrections extend the linear range of the QS calibration curve by a factor of over 100, and they can improve the accuracy up to a factor of ten in cases for which polychromatic effects are important.