This project explores the linear and non-linear regions in the absorption of sodium fluorescein. Both regions will be used to explain the limitations of the Beer-Lambert Law in the prospect of educating general chemistry level undergraduates. The experiment will address these regions using two approaches. The first approach presents absorption data acquired with a standard UV-Vis spectrometer that is fitted to a sigmoidal function in order to illustrate the linear and non-linear behavior of sodium fluorescein absorption spectra. Spectral analysis was further developed by testing the dependence of absorbance and emission on pH. In the second approach we will correlate the observed fluorescent path length in the sample generated from a collimated UV-LED source to the concentration. Because emission is dependent on concentration, the results obtained suggest that a visual correlation between the observed path length in the sample and concentration exists in the non-linear absorption regions of fluorescein.

Visual spectroscopy

243rd National Meeting (2012)

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