OXYGEN TENSION MEASUREMENT BY A METHOD OF TIME SELECTION USING THE STATIC PLATINUM ELECTRODE WITH ALTERNATING POTENTIAL

1. The possibility of obtaining sustained and reproducible results in the analysis of dissolved oxygen with simple platinum electrodes by means of the application of a periodic potential pattern was explored over a wide range of frequencies and with a variety of wave forms. 2. Satisfactory results were obtained by the application in the frequency range of 5 to 10 C.P.M. of a square wave consisting of a positive and a negative pulse with interposed shorting periods and observing the current flowing at the end of each successive negative pulse. This was found to be linearly proportional to O(2) concentration for a pulse duration of the order of 1 second when the RC constant of the circuit was sufficiently small. 3. An instrument was developed to provide the required wave form and record the terminal currents of the negative pulses. The instrument provides either for recording of current voltage curves (polarograms) or for continuous recording at a fixed voltage of diffusion limited current values. 4. Typical measurements of oxygen uptake with yeast suspensions illustrate the application of the technique to problems requiring frequent determinations during short intervals. 5. Applications of this technique to biological and other problems are indicated with its limitations.