AMPEROMETRIC MONITORING OF OZONE IN GASEOUS MEDIA BY GOLD ELECTRODES SUPPORTED ON ION-EXCHANGE MEMBRANES (SOLID POLYMER ELECTROLYTES)

An in situ amperometric sensor suitable for monitoring ozone in gaseous media is described. It consists of a porous gold working electrode (contacting the gaseous sample) supported on one surface of an ion exchange membrane (Nation 417) which serves as a solid polymer electrolyte. The other side of this membrane faces an internal electrolyte solution (1 M aqueous perchloric acid) containing the counter and reference electrodes. Amperometric measurements are performed at an applied potential of 0.5 V vs SCE, by inserting the sensor in a cell in which ozone-oxygen streams are fed with different controlled rates. A current sensitivity of 38 A M−1 cm−2 and a response time of 0.5 s are observed. The dynamic range turns out to extend up to 2 × 10−3 M (4.48 × 10−2 atm) with good linearity and a detection limit of 10−8 M (2.24 × 10−7 atm) is predicted for S/N = 3. These performances are compared with those provided by the corresponding gas-permeation membrane electrodes and by spectrophotometry methods employing suitable reagents. The effect of the flow rate on current responses is also discussed. © 1990, American Chemical Society. All rights reserved.