A versatile microstirrer and oxygen electrode system for a spectrophotometer cuvette.

A microstirring device is described which measures only 1 × 1 × 0.4 cm outsidedimensions and is thus suitable for insertion beneath most spectrophotometer cuvettes without displacing the cuvette from the light path and without the need for modification of the spectrophotometer. The top of the cuvette remains accessible for a specially designed cuvette lid and electrode. This combined equipment is particularly suitable for the simultaneous measurement of two parameters, one with the electrode and the other by spectrophotometry. The design of the lid also permits the addition of reactants, including O₂, during monitoring. The equipment has been used to measure the oxygen-binding isotherm of human hemoglobin using 0.1 mg of protein. The curve so obtained was identical with curves found in the literature and obtained under the same conditions of pH, temperature, etc.