| Summary: | 博士 === 國立臺灣師範大學 === 化學系 === 101 === This research reports the development of a micro gas chromatograph (μGC) that uses hybridization of both non-MEMS and MEMS-based analytical components for rapid and complex environmental volatile organic compounds (VOCs) analysis. The key tasks of this research are: (1) A first-generation μGC prototype was integrated by MEMS-fabricated key components such as multi-stage μ-preconcentrator, μ-column, μ-chemiresistor detector and hybridized with miniature pump and available μ-valves. The scrubbed air was used as the carrier gas in order to achieve smaller size, lightweight and long-term continuous operation. Vapor mixtures of 7 compounds were successfully separated and to be detected by the micro-chemiresistor in less than 2 minutes. The initial result indicates that the detection limits was 2.6 ng for n-octane. (2) Design and improve components of the first-generation μGC prototype: A μ-SPME array coated with in-situ-synthesized carbon adsorbent film replaces the original multi-stage μ-preconcentrator, a photoionization detector (PID) replaces the μ-chemiresistor detector to enhance stability of the μGC. The size of second-generation μGC prototype of fully function system is only 20 (L) × 10 (W) × 6 (H) cm. Vapor mixtures of 5 compounds are successfully separated and to be detected by the PID in less than 2 minutes. The detection limit was as low as 10 ppb in 1.0 L air sample for xylene. (3) The goal developed a ready-to-use and highly reliable third-generation μGC system with the non-MEMS components and a tablet computer embedded. This system consists of a multi-stage preconcentrator/injector module, a capillary column module with at-column heater configuration and a PID unit. As a result, the separation of the 10 compounds in only 2 minutes was achieved by using fast at-column heating. This detection limit ranged from 0.02 to 0.36 ppb was obtained with 1.0 L sample volume. The variation in peak areas ranged from 2.2% (benzene, n=120) to 5.2% (m-xylene, n=120) for continuous operation over 24 h. This instrumentation presents a stand-alone system that can provide hand-held operation without an external computer. (4) Field studies of real-time VOCs analysis were in a school adjacent to industrial area and a semiconductor fabrication clean room. In addition, canisters were collected and analyzed by GC-MS to provide the side-by-side comparisons. Field study Results indicate the trends of concentrations for all chemical species over time. Concentrations ranged from 0.1 to 4.8 ppb in the school and ranged from 0.3 to 20 ppb in the clean room. These data can provide a good indication of health assessments while exposure to VOCs. This prototype μGC demonstrated the capability for fast and continuous field analysis for complex VOCs in field studies.
|
|---|
