Practical Application of a Multi-Bed Adsorbent Tube Coupled with GC-MS for Low-Level VOCs Identification to Achieve Comprehensive Odor Management

We investigated the effectiveness of a multi-sorbent tube (M-Tube) to improve the sampling method for a wide range of odor-causing volatile organic compounds (VOCs) at low concentrations. The M-Tube applied in this study was a fixed tube packed with three adsorbents (Carboxen^®, Carbopack™, and Tenax^®-TA) in series. To verify the efficiency of the M-Tube, a comparative study was conducted against a single tube (S-Tube, Tenax^®-TA). A total of 42 target compounds were selected, including eight different chemical groups: terpenes, hydrocarbons, aldehydes, ketones, alcohols, esters, furans, and alkanes, to verify the effectiveness of the M-Tube. In the laboratory test, response factors, which are the ratios between output signals of gas chromatography by the sorbent-tube sample and the liquid-standard sample, for the M-Tube were higher than those for the S-Tube. The breakthrough volume of the M-Tube was higher than that of the S-Tube, indicating that the M-Tube had a relatively lower method detection limit. In the field application to the sewage treatment plant, 29 compounds were identified, and their concentration ranged from 0.3 to 98 ppbv (above MDL). The detected compounds were considered odor-causing VOCs, and the odor contribution of the compounds could be assessed. We ultimately concluded that comprehensive odor management could be established by determining trace VOCs.