Field evaluation of thermal and chemical desorption BTEX radial diffusive sampler radiello^®compared with active (pumped) samplers for ambient air measurements

Abstract

The performance of two types of radiello diffusive samplers, filled with a thermally desorbable adsorbent (graphitised carbon Carbograph 4) and with a solvent desorbable adsorbent (activated charcoal), respectively, have been evaluated for the monitoring of BTEX in ambient air, by comparison with active (pumped) samplers. A two year survey was carried out in Padua, a medium-sized town, in a traffic site, close to a busy crossroad. The concentrations of BTEX were measured for 15 campaigns, during which four series of radial diffusive samplers were exposed for 2 day, 7 day, 10 day and 14 day time periods, respectively. Every series of chemical desorption samplers included three replicates; thermal desorption samplers included six replicates, three of them filled with freshly conditioned cartridges and three filled with regenerated cartridges. No significant difference in the levels measured either by new or by regenerated cartridges has been found. During three campaigns (summer 2004, winter and spring 2005) two active (pumped) samplers were added for each sampling period. The diffusive uptake rates have been calculated and modelled under various conditions of concentration, temperature and exposure time. The effects of the environmental factors on the performances of both solvent and thermally desorbable samplers have been evaluated. The repeatability of the whole measurement process (sampling and analysis) was calculated for every sampling duration. The comparison of concentration levels measured by diffusive and active sampling methods shows correlation coefficients R >or= 0.98 (p<0.01) for all the compounds. The uncertainty of the diffusive sampling method under field conditions, using active sampling as the reference method, has been assessed according to the ISO 13752 requirements. On field relative expanded uncertainty for benzene has been found below 20%.

Measurement of benzene concentration in urban air using passive sampling

“…The correction for temperature performed for Q T each month does not fully reflect the monthly fluctuation in temperature and thus the fluctuation in Q T . This confirms that applying the average temperature to calculate Q T may lead to significant inaccuracy [28,[30][31][32][33][34][35].…”

Vertical concentration gradients of volatile organic compounds in two NS-oriented street canyons

“…The mean relative standard deviation (%MRSD) obtained for different sampling periods was in every case<6.5%. Numerous studies have thoroughly validated the use of Radiello® samplers for VOC monitoring (Pennequin-Cardinal et al 2005;Strandberg et al 2006;Plaisance et al 2008;Buzica et al 2008;Cocheo et al 2009), concluding that this method shows good agreement with the results obtained by active sampling and that it is valid for obtaining indicative measurements as regards Directive 2008/50/EC. For these reasons, we chose to set up only one sampler at each monitored level.…”

“…Cocheo et al (2009) studied the reproducibility of the Radiello® sampler with chemical desorption under field conditions. The mean relative standard deviation (%MRSD) obtained for different sampling periods was in every case<6.5%.…”

Ammonia emissions from a broiler farm: spatial variability of airborne concentrations in the vicinity and impact on adjacent woodland

“…Sampler mechanics rely on diffusion through an air gap ('tubes', e.g. Campbell 1988;Brown and Wright 1994;Cocheo et al 2008) and on permeation through a membrane ('badges', e.g. Ferm 1991;Löflund et al 2002).…”