(c) Observation of fluorescene
Prepare a solution of fluorescein by dissolving 5 milligrams (or spatula tip size) of the sample in
50 mL 0.1 M NaOH solution. Place the solution in a vial and place it on a black non-reflective surface,
such as a lab bench. Place a bright light source (sunny window works well) on the opposite side of the
bench from the observer and note the appearance of the solution. In this case, the color observed is
primarily due to absorbance of some wavelengths of visible light passing through the sample from the
light source.