https://ir.lib.ncu.edu.tw/handle/987654321/102073 Search the Channel s https://ir.lib.ncu.edu.tw/simple-search https://ir.lib.ncu.edu.tw/handle/987654321/102423 title: Two-dimensional gas chromatographic analysis of ambient light hydrocarbons abstract: 摘要： •The Deans switch was switched from the heart-cutting GC mode to the GC×GC mode to serve as a valve modulator.•A self-built Dean switch-GC×GC-FID system was used built to analyze light hydrocarbon VOCs at ambient levels.•A thermal desorption device was connect to the Dean switch GC×GC-FID system to allow in-line preconcentration of light hydrocarbons.•The orthogonality of volatility vs. adsorptivity was adopted, instead of the commonly used orthogonality of volatility vs. polarity, for GC×GC separation. Ambient level hydrocarbons lighter than C6 were analyzed by the Deans switch-modulated comprehensive two-dimensional gas chromatography (GC×GC) method with flame ionization detection (FID). A thermal desorption (TD) device built in-house connects the GC×GC system to pre-concentrate the target compounds at ambient levels prior to GC analysis. Because the conventional orthogonality based on polarity difference for normal GC×GC separation does not provide sufficient retention for the target compounds of extremely high volatility, the orthogonality of non-polar vs. adsorptive force was adopted instead. The system employed a 100% polydimethyl siloxane column serving as the first-dimension column to provide separation based on dispersive interaction, with a short PLOT column serving as the second-dimension column to provide the needed retention based on gas–solid adsorption interactions. The shortest possible length of the PLOT column was tested to minimize the modulation period (PM) and wraparound and, at the same time, to maintain the desired resolution. The tests led to the final optimal parameters of 1.1m for the PLOT column length, 9s for the PM, 0.013 for the modulation duty cycle (DC) and a modulation ratio (MR) of 3.7 with minimal wraparound. Important criteria for quality assurance of precision and linearity are reported. The low cost and ease of construction and operation make the in-house Deans switch TD-GC×GC-FID system practical and useful for the analysis of light hydrocarbons in urban or industrial environments. 其他題名： J Chromatogr A 出版者： Amsterdam: Elsevier B.V 出版日期： 2013-06-14 出處： Journal of Chromatography A, 2013-06, Vol.1294, p.122-129 版權： 2013 Elsevier B.V. 版權： 2014 INIST-CNRS 版權： Copyright © 2013 Elsevier B.V. All rights reserved. 識別號： ISSN: 0021-9673 識別號： ISSN: 1873-3778 識別號： EISSN: 1873-3778 識別號： DOI: 10.1016/j.chroma.2013.04.008 識別號： PMID: 23659976 識別號： CODEN: JOCRAM <br> Thu, 23 Apr 2026 03:08:23 GMT https://ir.lib.ncu.edu.tw/handle/987654321/102421 title: Characterization of thermal desorption with the Deans-switch technique in gas chromatographic analysis of volatile organic compounds abstract: 摘要： •Thermal desorption (TD) was characterized by the Deans-switch cutting technique.•The TD profile was sliced by the Deans switch for compositional study.•Havier compounds tent to trail behind lighter compounds during TD injection.•The slicing technique provided a quantitative means to assess the TD behavior. This study presents a novel application based on the Deans-switch cutting technique to characterize the thermal-desorption (TD) properties for gas chromatographic (GC) analysis of ambient volatile organic compounds (VOCs). Flash-heating of the sorbent bed at high temperatures to desorb trapped VOCs to GC may easily produce severe asymmetric or tailing GC peaks affecting resolution and sensitivity if care is not taken to optimize the TD conditions. The TD peak without GC separation was first examined for the quality of the TD peak by analyzing a standard gas mixture from C2 to C12 at ppb level. The Deans switch was later applied in two different stages. First, it was used to cut the trailing tail of the TD peak, which, although significantly improved the GC peak symmetry, led to more loss of the higher boiling compounds than the low boiling ones, thus suggesting compound discrimination. Subsequently, the Deans switch was used to dissect the TD peak into six 30s slices in series, and an uneven distribution in composition between the slices were found. A progressive decrease in low boiling compounds and increase in higher boiling ones across the slices indicated severe inhomogeneity in the TD profile. This finding provided a clear evidence to answer the discrimination problem found with the tail cutting approach to improve peak symmetry. Through the use of the innovated slicing method based on the Deans-switch cutting technique, optimization of TD injection for highly resolved, symmetric and non-discriminated GC peaks can now be more quantitatively assessed and guided. 其他題名： J Chromatogr A 出版者： Netherlands: Elsevier B.V 出版日期： 2016-09-02 出處： Journal of Chromatography A, 2016-09, Vol.1462, p.107-114 版權： 2016 Elsevier B.V. 版權： Copyright © 2016 Elsevier B.V. All rights reserved. 識別號： ISSN: 0021-9673 識別號： EISSN: 1873-3778 識別號： DOI: 10.1016/j.chroma.2016.07.070 識別號： PMID: 27492597 <br> Thu, 23 Apr 2026 03:08:22 GMT https://ir.lib.ncu.edu.tw/handle/987654321/102419 title: Assessment of carbon monoxide (CO) adjusted non-methane hydrocarbon (NMHC) emissions of a motor fleet - A long tunnel study abstract: 摘要： Speciated hydrocarbons (NMHCs) and CO were simultaneously measured by evenly distributed samples along the entire length (12.9 km) of the tunnel in different traffic conditions. Four passes (two round-trips) were made at four different fleet speeds (i.e., 45, 65, 75 and 85 km h−1). Individual NMHC and CO mixing ratios were observed to be sensitive to the fleet speed, which is compounded by driving conditions and traffic volumes. We propose using ratios of NMHCs to CO to cancel out the factor of traffic volumes to determine CO-normalized NMHC emissions, such that a less biased comparison can be made between different fleet speeds in this study and even between different studies. Moreover, to obtain robust CO-normalized NMHC emissions which are sufficiently representative of the fleet speeds, only samples collected deep inside the long-tunnels between 8 and 12 km were used. Of the 61 target NMHCs, isomers of butane, pentane, ethylene, acetylene and toluene were the most abundant species regardless of the driving conditions. We observed that different driving conditions not only affected the emission strengths but also altered the compositions of the NMHCs. To simplify the data analysis, the target NMHCs were classified into four chemical groups, i.e., alkanes, alkenes, aromatics and alkynes. For the slower and more congested driving condition (fleet speed = 45 km h−1), the CO-normalized NMHC emissions were the highest, with alkanes contributing to approximately 60% of the total NMHC levels, suggesting poorer fuel utilization at slower driving conditions. In terms of the CO-normalized ozone forming potentials (OFPs), the contribution of the alkanes diminished dramatically to approximately 9–22% despite their high weight percentage, whereas the contribution of the alkenes was enhanced significantly to 50–60% from their weight percent of only approximately 26%. Our total NMHC to CO ratios of 0.06–0.20 for the four fleet speeds generally fall within the range constrained by many other tunnel or chassis dynamometer studies; however, the sensitivity to the driving conditions and the robustness with the long-tunnel data are better demonstrated in this study. •Speciated NMHCs and CO were measured inside a long tunnel.•Using CO as a reference to cancel out the factor of traffic volume.•CO-normalized NMHCs were sensitive to the driving conditions – slow vs. fast.•Alkenes and aromatics are predominant in the OFPCO-normalized.•Our NMHC/CO for the four fleet speeds fall within the range from literatures. 出版者： Kidlington: Elsevier Ltd 出版日期： 2014-06-01 出處： Atmospheric environment (1994), 2014-06, Vol.89, p.403-414 資源來源： ScienceDirect - Freedom Collection 版權： 2014 Elsevier Ltd 版權： 2015 INIST-CNRS 識別號： ISSN: 1352-2310 識別號： EISSN: 1873-2844 識別號： DOI: 10.1016/j.atmosenv.2014.01.002 <br> Thu, 23 Apr 2026 03:08:21 GMT