Development of a new radial passive sampling device for atmospheric NOxdetermination

In this paper we used Na2CO3-impregnated silica as reactive substrate for the determination of atmospheric NOx(NO+NO2) by using a passive sampling device, with radial symmetry, which is unprecedented. We conducted laboratory and field tests at an urban setting, with co-located passive samplers and continuous measurements of NOxby a chemiluminescence detector, used as reference. The performance of the carbonate-based sorbent for the NOxsampler was evaluated in two different time frames (autumn 2016 and winter 2017), characterised by different environmental conditions. The comparison of the NOxconcentration levels measured by passive sampling, using Na2CO3as NOxsorbent, showed a close relationship with those obtained by the chemiluminescence analyzer. Validation experiments in the laboratory and in the field are reported together with the calculation of the diffusion-sampling rate of the samplers.