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ECN publication
Continuous monitoring of atmospheric HCl, HNO2, HNO3 and SO2 bywet-annular denuder air sampling with on-line chromatographic analysis
Published by: Publication date:
ECN 1995
ECN report number: Document type:
ECN-R--95-003 Other
Number of pages: Full text:
26 Download PDF  

An automatic system for the collection, in-line preconcentration andanalysis of acidifying atmospheric gases is described. Collection of HCl, HNO2, HNO3 and SO2 from ambient air is carried out with an annular wet denuder. After addition of an internal standard to the sample flow and conductivity suppression, preconcentration of the sample flow is performed by pumping a measured volume of the sample flow through an anion exchange concentrator column. Following the concentration step, the anions of the corresponding acids are analyzed by ion-chromatography with conductivity detection. The manifold described with two sample loops and two concentrator columns operating in parallel allows automatic collection and analysis of two air samples per hour. A computer program has been developed for automatic operation. It allows the system to run during extended periods without human assistance as all the functions, including data processing, are computer-controlled. Factors affecting the performance are reported. The detection limits achieved are 5.4, 12.1, 12.1 and 17 ng/m3 for HCl, HNO2, HNO3 and SO2 respectively, with relative standard deviations better than 4% at 1-2 mug/m3. Ambient measurements for Petten, The Netherlands, are presented showing the capability of the system for continuous monitoring of atmospheric acidifying gases. 5 figs., 1 tab., 12 refs.

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