Simultaneous Monitoring of ppmv Level Methane and ppbv Level VOCs Near Industrial Sources Using a Real-Time GC

Abstract

This paper presents the design and field monitoring results using a compact gas chromatograph equipped with a novel tandem sampler that enables the simultaneous and continuous analyses of methane at ppmv level and multiple volatile organic compounds (VOCs) at ppbv level. The tandem sampler consists of a capillary preconcentrator filled with multistage adsorbents and a subsequent sampling loop. In this system, ambient methane breakthroughs the adsorbents and fills the sampling loop while the ppbv levels of VOCs are preconcentrated by adsorbents. The field study was conducted in a developing industrial area near a midsize township that was surrounded by paddy fields. Continuous analysis data provided in 25 min intervals revealed the independent sources of various industrial chemicals. The rapid analysis capability of this instrument can establish concentration distribution patterns within only a few days of field study. Right skewed concentration distributions of low ppbv VOCs and a symmetrical Gaussian distribution of methane at ppmv using this single near real-time GC instrument. This study describes the development of a fast and cost-effective method to simultaneously assess the real-time variations in VOCs and methane in general environments.