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• Main Authors: Mei-Zhu Wang, 王美珠
• Other Authors: Jia-Lin Wang
• Format: Others
• Language: zh-TW
• Published: 2016
• Online Access: http://ndltd.ncl.edu.tw/handle/37910565924657970113

碩士 === 國立中央大學 === 化學學系 === 104 === This study aims to develop an automated gas chromatographic (GC) technique measuring volatile organic compounds (VOCs) in ambient air. This on-line automated GC technique was based on the existing NIEA method A715.15B, which is an off-line method based on gas chromatography – mass spectrometry (GC-MS) developed by the Environmental Analysis Laboratory of Taiwan EPA. In this newly developed method, ambient air was first quantitatively enriched by drawing through a sorbent trap kept at sub-ambient temperatures without using cryogens, followed by thermal desorption (TD) to a GC equipped with multiple detectors, i.e., MS, flame ionization detector, and halogen specific detector (XSD) to analyze 87 target VOCs. Because of the high humidity in ambient air and low sensitivity towards C1 - C4 species for mass spectrometry, both the heart-cut and flow-splitting techniques were used in GC configuration. The Deans switch cut the lighter effluents of C1 - C4 species from the DB-1 column to the PLOT for better separation. The C1 – C4 compounds were then simultaneously detected by both FID and XSD by splitting the effluent flow from the PLOT column for improved sensitivity and specificity, respectively. The remaining C5 – C12 spices from the DB-1 column were cut to MS in selected ion mode (SIM). The performance of the automated GC method was assessed from the aspects of water management, concentration calibration, precision and detection limits for the adequacy of field applications in monitoring industrial emissions. The precision expressed by the relative standard deviation (RSD%) ranged from 0.39% to 6.67% based on repeated analysis of standard mixtures at sub-ppb levels. The precision for the calibration curves ranged from 1.84% to 28% for 77 out of the 87 target compounds. Compared to the existing off-line method, the new on-line method successfully eliminated the need of cryogen and, at the same time, improved the sensitivity of C1- C4 compounds. The new method was then tested in the field for untended continuous monitoring of industrial pollutants.