Carbon Monoxide Diffusive Sampler
Carbon monoxide is still a mejor air pollutant in large cities, expecially in developing countries. One or two weeks exposure allow an estimate, if the 8 hours limit value is exceeded. The passive sampler for Carbon monoxide is based on the principle of the diffusion of CO molecules onto an absorbing medium, in this case Palladiumchloride. Metallic Palladium is formed, which can be determined by a specific reaction photometrically The passive samplers are composed of a polypropylene housing with an opening of 20 mm diameter. To reduce wind disturbance a glass fibre membrane is attached, supported by a wire net. To protect the sampler from weather influences, as well as minimising wind disturbance, a protective shelter has to be used.
Laboratory validation of CO sampler. The uptake rate is linear at least up to 20 mg/m3 for an exposure time of two weeks.
Calibration function: conc [mg/m3] = (mAbs -12.3) * 4.26 / hours
Working range: 0.5 — 20 mg/m3
Sampling time: 2— 4 weeks
Detection limit: 0.4 mg/m3two weeks exposure
wind speed: Influence of wind speed < 10% up to 4.5 m/sec using protection shelters
temperature: no influence between 5 to 40oC
humidity: no influence between 20 to 80%
before use: 6 months
after exposure: 3 months
Cross sensitivity: not known
Expanded uncertainty*: 22.6 % at concentration levels of 10 mg/m3