Characterization of industrial plumes of volatile organic compounds by guided sampling.

Instead of manual sampling in a random way near a source area, this study used trigger sampling guided by an analyzer at a fixed site near a refinery plant to obtain the chemical composition of volatile organic compounds (VOCs) representative of the source. The analyzer was built in-house to measure total VOC (TVOC) levels by subtracting methane from total combustible organic compounds (TOC) with flame ionization detection. The analyzer with minute resolution provided instantaneous measurements of TVOCs to trigger canister sampling at the moments of VOC plumes in a source area. The chemical composition of the 13 trigger samples were compared with the other non-trigger samples randomly collected either within the refinery or on an urban street. All samples were analyzed by gas chromatography-mass spectrometry/flame ionization detection (GC-MS/FID) for detailed speciation. High agreement in total VOC abundance between the analyzer and GC-MS/FID indicates internal consistency of the two techniques and the robustness of the TVOC analyzer to guide sampling of VOC plumes. The trigger samples showing very high consistency in the overall composition imply that sampling at the right moments of plume arrivals can facilitate characterization of the source profiles, which can hardly be achieved by random sampling. The coupling of the fast-and-slow analytical techniques to guide sampling is proven to be an effective means to probe source characteristics.