A new sorbent tube for atmospheric NOx determination by active sampling

In this paper we used hydrated mayenite as reactive substrate for NOx active sampling in the air, which is novel. The performance of the mayenite-based sorbent for the NOx tubes was evaluated in two different monitoring surveys (autumn 2015 and winter 2016), characterized by different environmental conditions. Sorbent tubes filled with mayenite were exposed simultaneously to triethanolamine (TEA)-based sorbent tubes and to a chemiluminescence detector, as reference. The comparison of the NOx concentration levels measured by active sampling, using mayenite as NOx sorbent, showed a close relationship with the chemiluminescence analyzer. The effect of the environmental conditions on the performance of both mayenite and TEA-based sorbent tubes was evaluated and limitations connected to the use of TEA were discussed.