Correction of inner-filter effect in fluorescence excitation-emission matrix spectrometry using Raman scatter
Tobias Larsson*, Margareta Wedborg, David Turner
Department of Chemistry, G?teborg University, Kemivagen 10, SE-41296 G?teborg, Sweden
This paper presents the inner filter effect correction method for the fluorescence excitation-emission matrix data obtained after spectrophotometry of water samples. The water samples do not obey Beer-Lambert’s law if the concentration of fluorescent dissolved organic matter is high and the data is said to have inner filter effects. In such condition, excitation and emission light is absorbed by the fluorescent dissolved organic matter depending upon its concentration. The author has presented a way to treat this data. After removal of inner filter effects, the data follows Beer-Lambert’s law. The mathematical formulation of the treatment uses Raman peak and is given below.
so is the untreated data, rMQ is the area under Raman peak of milli-q blank sample and ro is the area under Raman peak of the sample.
If the spectrophotometer does not have an in built correction factor for the excitation and emission wavelengths, it must also be taken into account. In case of experimental methods, the biases arise due to error in the measurement of cuvette dimensions. Since, the inner filter effects are insignificant in case of low concentration of fluorescent dissolved organic matter, so, some experimental techniques make use of dilution. But, the dilution causes contamination and the extent of dilution is also a problem. Adjustment of different sample parameters like pH is also a problem. So, the inner filter effect correction by the use of areas under Raman peaks for milli-q and water sample gives an unbiased correction.
Reviewer: Aamir Alaud Din