Parallel plate wet denuder coupled ammonia transfer device-conductivity detector for near-real-time monitoring of gaseous ammonia

Abstract

Gaseous ammonia (NH3) is a primary basic substance in the atmosphere, and its global emission has been increasing in recent decades. It is vital to continuously monitor the atmospheric NH3 to clarify the impact of NH3 on sensitive ecosystems. This paper proposes a simple gaseous NH3 monitor utilizing a parallel plate wet denuder (PPWD) and a conductometric flow injection analysis (FIA) with an ammonia transfer device (ATD). In the present study, water-soluble basic gases, NH3, are selectively detected by the conductivity detector (CD). The ATD-CD ammonium detector requires no coloring reagents commonly used in FIA. Five-day field measurement of ambient NH3 was successfully performed with 30 min time resolution. All the air samples over the observation period (n = 186) contained NH3 above the limit of quantification (11.4 nmol m−3). The NH3 data showed excellent agreement with the values using ion chromatography in the field measurements.

Keywords

• Ammonia
• Denuder
• Ammonia transfer device
• Conductivity detection
• Flow analysis