A New Gas-Particle Ion Chromatographic System for the Continuous Monitoring of Soluble Gases and Ionic Constituents of Particulate Matter

The chemical composition of ambient gases and particulate matter (PM) is of key interest and importance to researchers and regulators in ambient air programs worldwide. Inorganic anions and cations play a major role in the chemistry of gas and aerosols and are frequently the primary chemical species in fine PM (< 2.5 µm). Elucidating the chemistry of ambient aerosols is key to understanding their source, transport and potential health risks. A key initiative of the U.S. Environmental Protection Agency’s National Ambient Air Monitoring Strategy includes development of new monitoring technologies for accelerated, real-time reporting of air quality information.

In this presentation, a new automated gas-particle ion chromatographic (GP-IC) system is described for the measurement of acid gases, ammonia and soluble ionic constituents. The instrument operates with two independent parallel channels to collect and analyse gas and fine PM constituents. A parallel plate wet denuder collects the water-soluble gaseous constituents and directs them to an IC for measurement. An optional cyclone is used to remove large particles in a second channel, with a second wet denuder used to remove potentially interfering gases. The particle constituents are then collected and extracted in a novel continuous particle collector (PC) and directed to the IC for analysis. This GPIC system provides fully automated, continuous measurement of cations and anions in ambient aerosols with a high degree of robustness and flexibility. The limits of detection (LOD) for ammonium, sulfate, nitrate and oxalate are <0.1 ng/m3 with a 15 min analytical cycle and a sampling rate of 5 L/min.

⁽¹⁾ Telephone: (408) 481-4174; E-mail: rida.alhorr@dionex.com
⁽²⁾ Telephone: (408 ) 481-4253; E-mail: doug.later@dionex.com