| dc.description.abstract | Hazardous Air Pollutants (HAPs) are emitted in large quantities with industrial development, and the threat to public health has been an issue of great concern in recent years. In the past, the passive sampling technique, similar to the U.S. EPA Method 325A/B, was developed, including the determination of uptake rates for different adsorbent materials for a variety of volatile organic compounds (VOCs) under different climatic conditions.
Firstly, to broaden the range of target compounds, dual commercial adsorbent materials were combined into a tandom adsorbent tube for the complementary benefits and easier deployement and logistics. After excluding the species not passing the QA/QC criteria, the specific experimental uptake rates of the remaining target species were experimentally obtained for calculating concentrations of target compounds after passive sampling. Therefore, another important aspect of this study is to determine the uptake rates with a self-designed exposure chamber under different temperature and humidity conditions. An Automated Thermal Desorption (ATD) with Gas Chromatography-Mass Spectrometer (GC-MS) was used to analze the sorption tubes of passive sampling collected from the field.
The results showed that the composite materials could be used for passive sampling of 69 HAPs, nearly 30 more than the single adsorbent material, e.g., Carbopack X and Carboxen 569, which can only target 50 and 37 HAPs, respectively. The correlation coefficients of the composite materials were between 0.990~1.000, the detection limits were between 0.04 ppbv~0.99 ppbv, the relative standard deviations representing precision were between 0.32%~17.57%, and the recoveries representing accuracy were between 74.28%~121.61%. The samples were stored at 4°C and analyzed within 14 days to ensure the sample and thus data quality.
After thorough preparation, the composite materials were tested in various environments, such as nearby laboratories (organic, analytical, and biochemical laboratories), Academia Sinica, Taoyuan Guanyin Industrial Park. Tayuan Industrial Park, Changhua, and U.S. High School, Puxin High School, Yunlin Lunbei National High School, and Kaohsiung Renda Industrial Park. At some of these sites, both active sampling and passive sampling methods were used. In this study, there are four applications of passive sampling. Firstly, for long-term environmental exposure assessment; secondly, passive sampling with online thermal desorption (TD)-GC-MS or TD-GC with flame ionization detection (FID); thirdly, for emission source investigation; and fourthly, mutual validation with the online TD-GC-MS measurements. Comparing with the online GC method, passive sampling can avoid the complications in operation and maintenance of an instrument in the field. The field tests also revealed comparable results between the two methods when the mean concentrations were compared. As a result, passive sampling can effectively evaluate average concentrations of the target species over a prolonged period at minimal cost and effort, thus adding another useful tool to enhance environmental monitoring capability. | en_US |