We present the details for adapting a diode array UV-vis spectrophotometer to incorporate the use of polypropylene microcentrifuge tubes--fuge tubes--as cuvettes. Optical data are presented validating that the polyethylene fuge tubes are equivalent to the standard square cross section polystyrene or glass cuvettes generally used in spectrophotometers. The fuge tubes also can serve as reaction vessels, which permits the ready study of chemical systems involving heterogeneous phases by eliminating the need for tedious separations. (Contains 3 figures.)