Standardization of fluorescence excitation-emission-matrices in aquatic milieu
Charlotte Goletza,1, Martin Wagnera,*, Anika Gr?bela, Wido Schmidta, Nathalie Korfa, Peter Wernerb
a DVGW Water Technology Center Karlsruhe, Branch Dresden, Wasserwerkstraβe 2, 01326 Dresden, Germany
b Technical University Dresden, Institute for Waste Management and Contaminated Site Treatment, Pratzschwitzer Straβe 15, 01796 Pirna, Germany
Summary
This paper presents the pretreatment of samples subjected to fluorescence excitation emission spectroscopy. Due to differences in the detection systems of different spectrophotometers, the data is not reproducible. The differences in the detection systems cause two different kinds of deviations namely, excitation emission correction and fluorescence intensity correction. The deviations in the excitation emission correction and fluorescence intensity can be corrected using the following equations.
Fstand and Fobs are the standardized and observed fluorescence intensity. Cex and Cem are the corrected excitation and emission. Arearam is the area under raman peak at excitation wavelength 350 nm and emission wavelength ranging from 371 nm to 428 nm.
This standardized data does not follow Lambert-Beer law and this deviation in the data is called inner filter effect. The correction for the inner filter effects can be done using three different methods.
1. Gauthier
Gauthier correction can be achieved using following formula.
Fcorr and Fobs are the corrected and observed fluorescence intensities. Oex and Oem are the absorbance on excitation and emission, d is the thickness of the cuvette, w2 is the inner width of the cuvette and d2 is the thickness of the cuvette wall both measured in the direction of emission wavelength.
2. Lakowicz
This correction uses the following equation.
3. Larsson
This approach uses the raman peak for the inner filter effect correction. The equation is as under.
Using the corrected data, accurate measures of fluorescence intensity are obtained.
Reviewer: Aamir Alaud Din