A versatile approach for modifying standard optical cuvettes to permit their use as microscale reaction vessels in undergraduate chemistry labs is described. This approach is illustrated by a student experiment involving the solid-phase extraction of aqueous dye mixtures using a solution-deposited ion-exchange polymer (Nafion). Visual observations and photometric measurements are used to determine the film’s equilibration time, charge selectivity, and extraction efficiency for a cationic dye, methylene blue, both alone in solution and in the presence of an anionic dye, tartrazine. This experiment has been implemented in several different laboratory sections of a sophomore analytical chemistry course, yielding consistently good results and generating considerable student interest. Suggestions are provided for several variations and extensions of this general experimental scheme.
Paul Flowers (Thu,) studied this question.