When the limit of detection of the analytical method exceeds the concentration of the gas species present in the environment, quantitative analysis can be achieved by pre-concentrating the analyte during the sampling step. Triethanolamine (TEA) is a reagent able to efficiently and selectively collect NO2 present in the air, and has been used in different analytical methods[14–18].An effective procedure for the collection, preconcentration, and determination of gaseous NO2 involves the use of C-18 cartridges impregnated with triethanolamine solution [19]. Previous studies have shown that it is possible to actively collect the gas, with subsequent elution of the analyte using a methanolic solution [20].