揮發性有機化合物(Volatile organic compounds, VOCs)為臭氧與二次有機氣膠(Secondary organic aerosols, SOA)之前驅物，而多數VOCs物種在一般大氣環境中濃度為sub-ppb或~ppt (v/v)等級，低於多數氣相層析法(Gas chromatography, GC)所使用偵測器之偵測極限，因此在樣品導入GC作分析前，需使用裝載旋轉式六向閥(Six-port switching valve)的熱脫附儀(Thermal desorption, TD)，以化學吸附劑捕捉的方式進行樣品的前濃縮處理，惟長期使用下，旋轉閥本體與內部轉子在表面與氣流孔道所產生之磨損，往往造成氣流洩漏與橫竄等問題發生；除此之外，閥件系統中過多的管線接連處，使得無益體積(Dead volume)與額外管柱效應(Extra-column effect)造成了後端層析峰的拖尾。有鑑於此，本研究提出以無旋轉閥式的氣流導引熱脫附法(Flow-guided TD, FG-TD)解決上述閥件系統所面臨之問題。
FG-TD的進樣方式乃採Dean switch之配件Heart cut方法的精要，以三個微體積三通連接頭(Microvolume connector)與電磁三通閥所組成，藉由氣流的導引推動的方式達成樣品通過吸附管捕捉與熱脫附進樣，並有效地減少系統運作時所產生的磨耗。而與傳統六向閥為主的熱脫附儀作平行比對後，依舊能維持非常良好的表現，經由標準氣體測試，在高碳數分子(C6~C12)部分，對稱性由0.832提升至0.972，顯示在層析表現上獲得了良好的提升，且具有良好的再現性(RSD < 3 %)及線性關係(R2 > 0.99)，可作為未來濃縮儀進樣方式的選項之一。

Ambient volatile organic compounds (VOCs) are precursors of ozone and secondary organic aerosols (SOA). The concentrations of some of the common VOCs are usually at sub-ppb or even ppt(v/v) levels, rendering direct measurements below the detection limits of most detection methods for gas chromatography (GC). Using the thermal desorption (TD) method involving chemical sorbents and a 6-port switching valve provides a basic approach for sample pre-concentration prior to GC separation. However, the ware-and-tear of the rotor and the valve body after prolonged use often creates problems such as leakage, cross-channeling due to grooving, surface adsorption, etc. Excessive tubing connection around the switching valve also creates dead volume or the extra-column effect, resulting in peak tailing in GC analysis. In light of the aforementioned problems, a flow-guided TD device without using a switching valve is proposed and tested.
The flow-guided TD device is derived from the Deans switch, which was configured by three micro-volume Tee connectors and solenoid valves. The sample flow going through the sorption tube for trapping and the carrier gas flow after TD for injection were made possible by directing the flows through different paths with a guiding flow to achieve minimum wear-and-tear as well as dead volume. Comparison with the conventional TD design was revealed by the improved peak symmetry for C6-C12 peaks from 0.832 to 0.972 on average, significantly alleviating the problem of peak tailing. The average precision for the new TD method was better than 3% and the linearity (R2) was greater than 0.99.

[1] 環保署PM2.5資訊網

[2] http://ivy5.epa.gov.tw/epalaw/search/LordiDispFull.aspx?ltype=04&lname=0162

[3] http://highscope.ch.ntu.edu.tw/wordpress/?p=31047

[4] C.C. Chang, J.L. Wang, S.C. Lung, C.Y. Chang, P.J. Lee, C. Chew, W.C. Liao, Atmospheric Environment, December 2014, Pages 298-308

[5] A B. Guenther, P.R. Zimmerman,P.C. Harley,R.K. Monson, JCR, 20 July 1993 Pages 12609–12617.

[6] C.C. Chang, J.L. Wang, S.C. Candice Lung, S.C. Lu,C.J.Shiu,Atmospheric Environment, Volume 43, Issue 10, March 2009, Pages 1771-1778

[7] 美國環境法論集-湯德宗

[8] 台灣環境資訊中心

[9] A Guide to Interpreting Detector Specifications for Gas Chromatographs Technical Note, Agilent.

[10] 行政院環境檢驗所

[11] M.R. Ras, F.Bull, R.M. Marce, Trends in Analytical Chemistry, Vol. 28, No. 3, 2009

[12] M. Harper, Journal of Chromatography A, 885 (2000) 129–151

[13] T.Y. Chen, M.J. Li, J.L. Wang, Journal of Chromatography A, 976 (2002) 39–45

[14] K. Dettmer, W. Engewald, Anal Bioanal Chem (2002) 373 :490–500

[15] D.L. Heavner, M.W. Ogden, P.R. Nelson, Environ. Sci. Technoi. 1992, 26, 1737-1746

[16] States Patent 2,858,851 PUSH-PULL VALVE yJames W. F. Holl, r'Iemple, City, Calif. f Applicatiouseptember 16,-1-954, Serial No. 456,435

[17] States Patent ,1968 J. G. PECIS 3,387,631 PUSH-PULL VALVE Filed Nov. 5, 1965 *5 6 Sheets-Sheet 1 43 23

[18] R.K.Hay, P.Lemeunier, Journal of Scientific Instruments,1966.43(9),652.

[19] L.M. M., chromatographic sampling valve. 1961, google patents.

[20] States Patent, l966 H. G. BoET'rGr-:R 3,267,736, chromatographic sampling valve.

[21] Valco,Instruments.CO.Inc.VICI.AG.International.

[22] www.lih-kuang.com/materials/vespel.html

[23] 戴順育，氣相層析技術應用於揮發性有機化合物分析方法中熱脫附行為之診斷，2014

[24] 王姵絜，多孔材料用於揮發性有機物質的吸脫附特性研究，2013

[25] R. Barro, J. Regueiro, M. Llompartb, C.G. Jaresb Journal of Chromatography A, 1216 (2009) 540–566

[26] 黃映雪, 應用Heart-cut 技術診斷揮發性有機化合物之熱脫附行為,2009

[27] On-site monitoring of volatile organic compounds as hazardous
air pollutants by gas chromatography

[28] J.L. Wang, C.C. Changb, K.Z. Lee, Journal of Chromatography A, 1248 (2012) 161–168

[29] Y. Yokouch, Y. Ambe, T. Maeda, Anlytical Sciences 1986, VOL. 2

[30] W.A. McClenny, Anal. Chem. 1984 56, 2947-2951

[31] N. Schmidbauer, M Oehme, Journal of High Resolution ChromatographyVolume 9, Issue 9, pages 502–505, September 1986

[32] J.M. Sanchez, R.D. Sacks, Anal. Chem. 75 (2003) 978.

[33] A.H. Goldstein, B.C. Daube, J.W. Munger, S.C. Wofsy, J.Atmos. Chem. 21 (1995)43.

[34] J.P. Greenberg, D. Helming, P.R. Zimmerman, J. Geophys. Res.101 (1996) 14581.

[35] D. Klemp, D. Kley, F. Kramp, H.J. Buers, G. Pilwat, F.Flock,
H.W. Patz, A. Volz-Thomas, J. Atmos. Chem. 28 (1997) 135

[36] L.M. Cardenas, J.F. Austin, R.A. Burgess, K.C. Clemitshaw,
S. Dorling, S.A. Penkett,R.M. Harrison, Atmos. Environ. 32 (1998)
3339.

[37] M.H. Habram, J. Slemr, T. Welsch, Journal of High Resolut.
Chromatogr. 21 (1998) 209

[38] J.L.Wang, C.J. Chang, W.D. Chang, C. Chew, S.W. Chen,
Journal of Chromatogr. A 844(1999) 259

[39] Ribes, G. Carrera, E. Gallego, X. Roca, M.J. Berenguer, X. Guardino, J. Chromatogr. A 1140 (2007) 44.

[40] J. Pollmann , D. Helmig , J. Hueber, D. Tanner, P.P. Tans, Journal of Chromatography A, 1134 (2006) 1–15

[41] J.L. Wang, C.H. Wu, Analytica Chimica Acta 461 (2002) 85–95

[42] J.L. Wang, G.Z. Dina, C.C. Chanb, Journal of Chromatography A, 1027 (2004) 11–18

[43] J. Pollmann , D. Helmig, J. Hueber, D. Tanner, P. P. Tans, Journal of Chromatography A, 1134 (2006) 1–15

[44] D. Tanner, D. Helmig , J. Hueber , P. Goldan, Journal of Chromatography A, 1111 (2006) 76–88

[45] J.L. Wang, W.L. Chen, Y.H. Lin, C.H. Tsai, Journal of Chromatography A, 896 (2000) 31–39

[46] Y.C. Su, H.M. Kao, J.L. Wang, Journal of Chromatography A, 1217 (2010) 5643–5651

[47] 黃新維，利用中孔徑矽分子篩MCM-41分離、量測大氣二氧化碳，2010

[48] 廖千宜，多孔材料吸附特性研究與氣體線上校正方法探討，2009

[49] 陳彥呈，以NCLA9K4活性碳作為VOC濃縮介質與熱脫附方法之改良，2011

[50] 吳東明，中孔徑矽分子篩與微孔徑碳分子篩使用於VOC線上濃縮之吸附性，2005

[51] J.L. Wang , S.W. Chen, C. Chew, Journal of Chromatography A, 863 (1999) 183–193

[52] S.C. Terry, J.H. Jerman, J.B. Angell, IEEE Trans. Electron. Dev. 26 (1979) 1880

[53] S. Ali, M. Ashraf-Khorassani , L. T. Taylor , M. Agah, Sensors and Actuators B 141 (2009) 309–315

[54] B. Alfeeli, D. Cho, M. Ashraf-Khorassani ,
L. T. Taylor , M. Agah, Sensors and Actuators B 133 (2008) 24–32

[55] S. Narayanan, B. Alfeeli, M. Agah, Procedia Engineering 5 (2010) 29–32

[56] H. Lahloua,∗, J.-B. Sanchezb, X. Vilanovaa, F. Bergerb, X. Correiga, V. Fierroc, A. CelzardcSensors and Actuators B 156 (2011) 680– 688

[57] W. Kuipers, J. Muller, Talanta 82 (2010) 1674–1679.

[58] R.S. Jian, R.X. Huang, C.J. Lu, Talanta 88 (2012) 160–167.

[59] J.B. Sanchez, F. Berger, Talanta 80 (2009) 385–389.

[60] G.R. Lambertus, A. Elstro, K. Sensenig, J. Potkay, M. Agah, S. Scheuering,

[61] K. Wise, F. Dorman, R. Sacks, Anal. Chem. 76 (2004) 2629–2637.

[62] V. Fierro, et al., Methodical study of the chemical activation of Kraft lignin withKOH and NaOH, Microporous and Mesoporous Materials 101 (2007) 419–431.

[63] H.N. Talylor, et al., Adsorption of butadiene on activated charcoal, Industrialand Engineering Chemistry 39 (July (7)) (1947) 871–876.

[64] Sanchez, J.M. and R.D. Sacks, Analytical chemistry, 2003. 75(4): p. 978-985.

[65] T.M. Wu, G.R. Wu, H.M. Kao, J.L. Wang, Journal of Chromatography A, 1105 (2006) 168–175

[66] Y.C. Su, W.T. Liu, W.C. Liao, S.W. Chiang, J.L. Wang, Journal of Chromatography A, 1218 (2011) 5733–5742

[67] 蘇源昌，自動氣相層析質譜儀於揮發性有機化合物之分析技術與應用，2011

[68] Dolan, R.M.M.a.J.W., LCGC Trobleshooting, 2004. 1050.

[69] C.H. Wang, C.C. Chang, J.L. Wang, Journal of Chromatography A, 1087 (2005) 150–157

[70] C.H. Wang, C.C. Chang, J.L. Wang, Journal of Chromatography A, 1163 (2007) 298–303

[71] 王介亨,心切技術應用於二維氣相層析揮發性有機化合物分析-概念設計與應用，2008

[72] Deans, D. R., Chromatographia 1968, 1, 18-22

[73] Sampling valve, Valco

[74] 恆誼儀器公司

[75] C.h. Je, R. Stone, S. G. Oberg, Science of the Total Environment 382 (2007) 364–374

[76] K. N. Whitley. A. F. Blackwell, Journal of Visual Languages and Computing (2001) 12, 435}472

[77] 行政院環保署公告訂定「空氣中有機光化前驅物檢測方法－氣相層析／火焰離子化偵測法（NIEAA505.12B)」