Abstract
This research probed development of a sample pre-concentration system (cryogen-free) coupled with automated GC/MS for measurement of volatile organic compounds(VOCs) in ambient air. The sample pre-concentration system includes refrigeration and the multiple-bed adsorbent technique with low temperature condensation and adsorption phenomenon to concentrate VOCs. The system offers several merits such as being automatic, ability to use in combination with commercial instruments, works cryogen-free at condensation temperature of < -40 0C, overcomes the incomplete adsorption of the the C2 compounds onto the multiple-bed adsorbent at room temperature and is relatively low-cost. With canister sampling and the automated GC/MS, 55 kinds of VOCs constituting 36 kinds of the non-polar VOCs (C1-C8),using TO-14A, and 19 kinds of polar VOCs (C2-C7) were analyzed. QA/QC data implied that the system meets the analytical performance grade of EPA methods. The MDL is in the range of 1.9~11.2ppb. A successful application of this method is made to analyze the VOCs in the ambient air from the sewer systems and sewage treatment plant of hi-tech industrial park. In the sewage treatment plant, 11 kinds of VOCs were measured in air sample, among which acetone is the major pollutant, detected with a highest concentration of 512.2 ppbv.