We have not written an experiment that explores fluorescence quantitatively.

However, if you are interested in relating concentration and fluorescence by doing a “Beer’s Law type” experiment using a dilution series, fluorescein works well. You can purchase fluorescein from Flinn Scientific. Mix up a 1 mg/mL stock solution of fluorescein using ethanol or methanol as a solvent. You can then dilute this stock using water. Linear results can be seen with concentrations in the parts per million range. You will need to determine the best concentrations for your GDX-SVISPL.

Please see the following link for ideas on how to use fluorescence in the classroom:

We have not developed a quantitative chemistry experiment for fluorescence because fluorescence is a complicated phenomenon and the GDX-SVISPL was not designed to be a research grade fluorometer.

For example, quantitative fluorescence measurements rely on knowing the quantum yield of the compound (similar to the idea of an extinction coefficient in Beer’s Law, but origin is completely different):

Fluorescence intensity = (Intensity of incident light)*(quantum yield of fluorescence)*(1-exp^(extinction coefficient*path length*concentration))
where the latter is derived from Beer’s law.

Quantifying fluorescence can be difficult because the intensity values, as well as the quantum yield values, are very sensitive to: 1) quenching by impurities in the compound, 2) temperature fluctuations of the sample, 3) non-linearity of the calibration curve especially at higher concentrations of sample, 4) fluorescent impurities in the solvent.

We do offer a fluorescence spectrometer for doing quantitative analysis: Vernier Fluorescence/UV-VIS Spectrophotometer (VSP-FUV)