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Ou-Yang CF, Chen YJ, Hsieh HC, Lee CT, Chi KH, Lin NH, Chang CC, Wang JL. Identification of organic constituents on atmospheric particulate matter in the East Asian background air of free troposphere by GC×GC-TOFMS. CHEMOSPHERE 2024; 364:143095. [PMID: 39146995 DOI: 10.1016/j.chemosphere.2024.143095] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/28/2024] [Revised: 08/12/2024] [Accepted: 08/13/2024] [Indexed: 08/17/2024]
Abstract
The presence of organic compounds on the particulate matter (PM) or aerosols can arise from the condensation of gaseous organic compounds on the existing aerosols, or from organic precursors to form secondary organic aerosols (SOA) through photochemistry. The objective of this study is to characterize organic constituents on aerosols relevant to their emission sources and the key compounds revealing the evolution of aerosols with the use of a novel analytical technique. A time-of-flight mass spectrometry (TOFMS) coupled with comprehensive two-dimensional gas chromatography (GC×GC) was developed using a flow type of modulator instead of a thermal type as a prelude to field applications without the need for cryogen. The methodology of GC×GC-TOFMS is discussed in this study in detail. Since the coarse PM (PM10-2.5) may exhibit with a relatively high OC content compared to PM2.5, the GC×GC results have been obtained by analyzing PM10 samples collected in parallel with OC/EC analysis of PM2.5 samples at the Lulin Atmospheric Background Station (LABS, 23.47°N, 120.87°E, 2862 m ASL) as the high-mountain background site in East Asia. We found that the organic analytes were in a majority in the range of 12-30 carbon numbers falling in the category of semi-volatile organic compounds (SVOCs) with 43 compounds of alcohol, aldehyde, ketone, and ester varieties if excluding alkanes. Intriguingly, trace amounts of plasticizers and phosphorus flame retardants such as phthalates (PAEs) and triphenyl phosphate (TPP) were also found, likely originating from regions involved in open burning of household solid waste in Southeast Asia or e-waste recycling in southern China and along the long-range transport route. Compounds such as these are unique to the specific sources, demonstrating the wide spread of these hazardous compounds in the environment.
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Affiliation(s)
- Chang-Feng Ou-Yang
- Department of Atmospheric Sciences, National Central University, Taoyuan, 32001, Taiwan; Center for Environmental Monitoring and Technology, National Central University, Taoyuan, 32001, Taiwan.
| | - Yi-Jun Chen
- Department of Chemistry, National Central University, Taoyuan, 32001, Taiwan
| | - Hsin-Cheng Hsieh
- Department of Chemistry, National Central University, Taoyuan, 32001, Taiwan
| | - Chung-Te Lee
- Graduate Institute of Environmental Engineering, National Central University, Taoyuan, 32001, Taiwan
| | - Kai-Hsien Chi
- Institute of Environmental and Occupational Health Sciences, National Yang Ming Chiao Tung University, Hsinchu, 30010, Taiwan
| | - Neng-Huei Lin
- Department of Atmospheric Sciences, National Central University, Taoyuan, 32001, Taiwan; Center for Environmental Monitoring and Technology, National Central University, Taoyuan, 32001, Taiwan; Department of Chemistry, National Central University, Taoyuan, 32001, Taiwan
| | - Chih-Chung Chang
- Research Center for Environmental Changes, Academia Sinica, Taipei, 11529, Taiwan
| | - Jia-Lin Wang
- Center for Environmental Monitoring and Technology, National Central University, Taoyuan, 32001, Taiwan; Department of Chemistry, National Central University, Taoyuan, 32001, Taiwan.
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Characterization of thermal desorption with the Deans-switch technique in gas chromatographic analysis of volatile organic compounds. J Chromatogr A 2016; 1462:107-14. [PMID: 27492597 DOI: 10.1016/j.chroma.2016.07.070] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2016] [Revised: 07/26/2016] [Accepted: 07/26/2016] [Indexed: 11/23/2022]
Abstract
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.
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Ou-Yang CF, Liao WC, Wang PC, Fan GJ, Hsiao CC, Chuang MT, Chang CC, Lin NH, Wang JL. Construction of a cryogen-free thermal desorption gas chromatographic system with off-the-shelf components for monitoring ambient volatile organic compounds. J Sep Sci 2016; 39:1489-99. [DOI: 10.1002/jssc.201501336] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2015] [Revised: 01/25/2016] [Accepted: 02/15/2016] [Indexed: 11/08/2022]
Affiliation(s)
- Chang-Feng Ou-Yang
- Department of Chemistry; National Central University; Taoyuan Taiwan
- Department of Atmospheric Sciences; National Central University; Taoyuan Taiwan
| | - Wei-Cheng Liao
- Department of Chemistry; National Central University; Taoyuan Taiwan
| | - Pei-Chieh Wang
- Department of Chemistry; National Central University; Taoyuan Taiwan
| | - Gang-Jei Fan
- Department of Chemistry; National Central University; Taoyuan Taiwan
| | - Chien-Cheng Hsiao
- Department of Chemistry; National Central University; Taoyuan Taiwan
| | - Ming-Tung Chuang
- Graduate Institute of Energy Engineering; National Central University; Taoyuan Taiwan
| | - Chih-Chung Chang
- Research Center for Environmental Changes; Academia Sinica; Taipei Taiwan
| | - Neng-Huei Lin
- Department of Atmospheric Sciences; National Central University; Taoyuan Taiwan
| | - Jia-Lin Wang
- Department of Chemistry; National Central University; Taoyuan Taiwan
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Liao WC, Ou-Yang CF, Wang CH, Chang CC, Wang JL. Two-dimensional gas chromatographic analysis of ambient light hydrocarbons. J Chromatogr A 2013; 1294:122-9. [DOI: 10.1016/j.chroma.2013.04.008] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2013] [Revised: 04/03/2013] [Accepted: 04/04/2013] [Indexed: 11/29/2022]
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Seeley JV. Recent advances in flow-controlled multidimensional gas chromatography. J Chromatogr A 2012; 1255:24-37. [PMID: 22305357 DOI: 10.1016/j.chroma.2012.01.027] [Citation(s) in RCA: 70] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2011] [Revised: 12/20/2011] [Accepted: 01/10/2012] [Indexed: 10/14/2022]
Abstract
The continued development of flow-controlled two-dimensional gas chromatography (2-D GC) is reviewed, with a special emphasis on results published from 2001 through 2011. Heart-cutting 2-D GC continues to be used for isolating selected components in complex mixtures. The programmable and highly precise flows and temperatures produced by modern gas chromatographs have made it easier to selectively transfer analytes to the secondary column and to backflush unwanted components from the primary column. Several new Deans switch interfaces for performing heart-cutting 2-D GC have been introduced, with most attention given to devices that integrate the flow connections into a single unit. Heart-cutting 2-D GC has been used to isolate analytes in a wide variety of complex mixtures including fuels, industrial feedstocks, fragrances, and environmental extracts. Valve-based comprehensive 2-D GC (GC×GC) was also actively developed in the past decade. Valve-based modulation is a simple way to generate GC×GC separations without using cryogenic fluids. More than ten new valve-based modulators were introduced. Diaphragm valves fitted with sample loops are the most common low duty cycle modulators, whereas fluidic modulators that employ differential flow conditions are the most common high duty cycle modulators. Applications of valve-based GC×GC include analysis of hydrocarbon mixtures, essential oils, and environmental samples.
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Affiliation(s)
- John V Seeley
- Oakland University, Department of Chemistry, Rochester, MI 48309, USA.
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Full-range analysis of ambient volatile organic compounds by a new trapping method and gas chromatography/mass spectrometry. J Chromatogr A 2011; 1218:5733-42. [DOI: 10.1016/j.chroma.2011.06.067] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2011] [Revised: 06/13/2011] [Accepted: 06/16/2011] [Indexed: 11/21/2022]
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Wang CH, Chiang SW, Wang JL. Simultaneous analysis of atmospheric halocarbons and non-methane hydrocarbons using two-dimensional gas chromatography. J Chromatogr A 2010; 1217:353-8. [DOI: 10.1016/j.chroma.2009.11.053] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2009] [Revised: 11/17/2009] [Accepted: 11/17/2009] [Indexed: 11/25/2022]
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Wang CH, Chang CC, Wang JL. Devising an adjustable splitter for dual-column gas chromatography. J Chromatogr A 2007; 1163:298-303. [PMID: 17651745 DOI: 10.1016/j.chroma.2007.06.070] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2007] [Revised: 06/12/2007] [Accepted: 06/19/2007] [Indexed: 10/23/2022]
Abstract
A flow controlled adjustable splitter was configured from a Deans switch and employed in an automated dual column gas chromatographic (GC) system for analyzing mono-aromatic compounds. Volatile organic compounds (VOCs), thermally desorbed from the sorbent trap, were split by the adjustable splitter onto two columns of different phases for separation and then detection by flame ionization detection (FID). Unlike regular splitters in which the split ratio is passively determined by the diameter and/or length of the connecting columns or tubing, the split ratio in our adjustable splitter is controlled by the auxiliary flow in the Deans switch. The auxiliary flow serves as a gas plug on either side of the column for decreasing the sample flow in one transfer line, but increasing the flow in the other. By adjusting the auxiliary flow and therefore the size of the gas plug, the split ratio can be easily varied and favorable to the side of no auxiliary gas. As an illustration, two columns, DB-1 and Cyclodex-B, were employed in this study for separating benzene, toluene, ethylbenzene, xylenes, denoted as BTEX, in particular the structural isomers of o-, m-, p-xylenes. This configuration demonstrates that BTEX cannot be fully separated with either column, but can be deconvoluted by simple algebra if dual columns are used with a splitter. The applicability of the proposed concept was tested by analyzing a gas standard containing BTEX at different split ratios and with various sample sizes, all leading to a constant ratio of m-xylene versus p-xylene.
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Affiliation(s)
- Chieh-Heng Wang
- Department of Chemistry, National Central University, Chungli 320, Taiwan
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