| Improvements of inner filter effect (IFE) corrections of fluorescence measurements were accomplished over significantly wider linear ranges (of corrected fluorescence intensity versus absorbance) by using effective geometric parameters, as compared to results published in literature, in the case of right angle geometry. The determination of effective geometric parameters can be achieved by using a 2 dimensional cell shift device, as well as using mathematic optimization. Results of the two approaches agree well with each other. The sample systems we used include 6 sample series designed for IFE corrections involving primary IFE only, as well as both primary and secondary IFEs. The sample systems we used demonstrated significant improvements of IFE corrections.;We checked the validity of our IFE correction methods by comparing the slopes of correction curves to the "true slopes" of the line of very dilute samples with negligible IFE effect. It was found that the slopes of correction are very close to the "true slopes". We found that for a given instrumentation and solvent, the effective geometric parameters determined by both cell shift and mathematic optimization are in good agreement and result in much improved IFE correction. We extended the applications of IFE correction equations for right angle geometry to substantially wider ranges of optical density of the sample solutions studied.;One of the most important results of our work is that IFE correction equations based on ideal beam conditions (i.e. collimated, uniform excitation and emission beam) can be used on non-collimated and non-uniform beam conditions, which is the case for most commercial fluorimeters. Furthermore, this study provided a way of overcoming the difficulties of determining geometric parameters that are critical to IFE corrections. |
