Abstract
Different methods were tested for the determination of low NO2 levels in ambient air using solid adsorbent sampling. The most promising technique was found to be adsorption on a diphenylamine(DPA)-coated surface. The formed reaction products were quantified by high-performance liquid chromatography. Compared with classical wet-chemical techniques considerably lower detection limits and blank values were obtained (typically <0.05 Μg NO2/m3 at a sample volume of ≥1 m3 and a sample flow rate of 1–2 l/min). At levels larger than 1–2 Μg NO2/m3 the results from ambient air measurements were in good agreement with a modified Griess-Saltzmann procedure using impinger sampling. A detailed description of the sampling conditions, working procedure and recovery rates are given. Other solid adsorbent sampling techniques based on triethanolamine-coated solids were also tested but in general the collection efficiency was unsatisfactory. The described DPA method is well-suited for remote area sampling of concentrations well below 1 Μg NO2/m3.
Published Version
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