Deoxygenation of solutions for transient studies

An all-glass vessel which allows a solution to be freed of dissolved oxygen was constructed. The main advantage of this apparatus is the ability to deoxygenate the system without the addition of a reducing agent. This might be desirable in order to avoid possible interactions of highly reactive systems or excited states with foreign additives. Other advantages of the method over the customary freeze-pump-thaw method or vigorous bubbling by an inert gas are (i) the ability to deoxygenate solutions of sensitive biological macromolecules by gentle means; (ii) the ability to add aliquots of reagents to a solution without exposing it to the ambient atmosphere; and (iii) the all-glass vessel's leak-proof quality toward the atmosphere for hours after freeing the solution from oxygen. The apparatus should be useful for spectroscopic, i.e., absorption and emission, studies. It was tested by measuring the 10-ms triplet lifetime of Zn-protoporphyrin which was substituted for the native Fe-porphyrin in myoglobin and the 5-ms lifetime of Zn-octaethylporphyrin in toluene.