A method for titrating oxygen-sensitive organic redox systems with reducing agents in solution.

A long-term need has existed in the study of complex redox systems, such as the electron-transferring enzymes found in biological systems, for an accurate method of titrating a system through its various oxidation states using small increments of a reducing agent in solution (1). The methods to be described in this and the accompanying paper (2) were developed concurrently to perform this task. The method to be described in this paper makes adequate provision for flushing and exclusion of molecular oxygen, for addition of accurately measured increments of a standardized reducing agent, and for spectrophotometric observation of the solution being titrated. The general method, however, might easily be adapted for electrochemical measurements, paramagnetic resonance spectroscopy, or some other method of observation.