Author Response for "investigating Challenges with Scattering and Inner Filter Effects in Front‐face Fluorescence by PARAFAC"

The use of front‐face fluorescence spectroscopy, and three‐way chemometric analysis (like PARAllel FACtor analysis, PARAFAC), has been successfully applied for the analysis of unpretreated samples in the fields of food and environmental analysis. It would be desirable to evaluate the potential of this approach for the analysis of any real sample in any field of research. Even in the simplest of the real samples acquired with front‐face, the presence of scattering and inner filter effects will occur, potentially hampering the subsequent data analysis due to deviations from Beer‐Lambert's law. This paper addresses these concerns in practice, proposing a strategy of spectral preprocessing to mitigate these effects. This is done by measuring several data sets with different levels of scattering and inner filter effects by fluorescence in excitation‐emission mode. The results show that the occurrence of these interferents (sometimes neglected with front‐face mode) affects the fluorescence signal and interferes with any traditional analysis on these data, as much as they hamper the successful use of methods like PARAFAC. The proposed preprocessing strategy is based on one of the most traditional correction for the inner filter effect with right‐angle mode. However, we suggest applying a tunable factor, b, that will account for the degree of deviation from linearity between concentration of a given analyte and its fluorescence signal. It is demonstrated that by choosing a proper b‐value, this correction helps in finding an acceptable solution for the PARAFAC algorithm, in line with Beer‐Lambert's law.