Development and evaluation of a small active ozone sampler

Current methods for monitoring ambient and microenvironmental ozone include continuous measurement instruments, such as UV photometric and chemiluminescence monitors, open-path diffusion optical absorption spectrometer, and passive sampling devices. This paper introduces a new small active ozone sampler that utilizes a single etched glass denuder as the collection substrate. The denuder is coated with a solution containing the nitrite ion that reacts with ozone to produce nitrate. It is attached to a small personal pump driven by a 9-V battery. When compared with UV photometric measurements, the active sampler demonstrated very good accuracy (active sampler/UV photometer = 0.94-1.00) and precision (%P = +/-4.1-6.5%) under laboratory and ambient conditions for sampling period from 1 to 60 h. The Harvard active ozone sampler performed as well as the Timed Exposure Diffusion sampler, the only other active ozone sampler currently in use. Sampler performance was found to be insensitive to variations in relative humidity (active sampler/UV photometer approximate to 1.00 at 20-80% RH) except at very low relative humidity (active/UV photometer = 0.81 at 12%). A low limit of detection of 10 ppb.h allows for sampling at very low concentrations.