The internal consistency of the Analyst diffusive sampler - a long-term field test

A recently developed diffusive sampler, intended for the use in long-term ambient measurements of volatile aromatic hydrocarbons, has been tested in order to determine the upper limits of sampling capacity. A test, carried out along a 12 months period, has been performed in order to evaluate these limits in terms of its "internal consistency" (i.e. checking if the sum of the amounts of a given pollutant, determined in shorter consecutive periods, matches the amount determined with a single long-period exposure). Results demonstrate that the uptake rate of the device, in a real (indoor) atmosphere, is a constant value along about 8 months for benzene and along about 10 months for toluene, while the upper limit for higher homologous species has not been reached after a one year exposure time at conditions typical of ambient concentrations. This means that the device can be successfully used for several months, thereby allowing low cost determinations of ambient BTX concentration.