A Pulse Amperometric Sensor for the Measurement of Atmospheric Hydrogen Peroxide

Abstract

Gaseous H₂O₂ is sampled through a Nafion membrane diffusion scrubber while 1 mM HCl is maintained stationary in the scrubber. After a preselected preconcentration time (typically, 5−10 min), a valve is opened to allow the scrubber liquid to flow by gravity over an electrochemical H₂O₂ sensor for a brief period. The miniature flow-over sensor consists of a Pt/Rh wire working electrode and a Pt wire counter electrode wound respectively on separate segments of a Nafion solid polymer electrolyte tubing supported on a Ag/AgCl wire reference electrode. A simple electronic interface and a personal computer are used to control and record the electrochemical measurement. The liquid phase detection limit for this sensor is ∼30 nM H₂O₂ in the anodic oxidation mode. For a 9 min gas sample preconcentration period, the LOD (S/N = 3 criterion) is 0.11 ppbv H₂O₂(g). Ambient H₂O₂ data obtained with this instrument were in excellent agreement with those obtained by an established fluorometric technique in a blind intercomparison.