摘要(英) |
To promptly identify emission sources of ozone precursors and clarify the relationship between volatile organic compounds (VOCs) and ozone formation, the Ministry of Environment (former Environmental Protection Administration) established multiple Photochemical Assessment Monitoring Stations (PAMS) in Taiwan. These stations continuously monitor 54 VOCs hourly. In addition to PAMS, the Ministry of Environment also enacted regulations to monitor VOCs listed as hazardous air pollutants (HAPs). These toxic VOCs range from sub-ppb (v/v) to ppt (v/v), thus requiring the thermal desorption (TD) technique to preconcentrate air samples. This study builds on previous laboratory experience to develop a low detection limit TD system, coupled with a commercial GC/MS system for online monitoring. The instrument includes features such as temperature control, leak test, flow control, multi-sampling, etc.
The developed TD system was tested following the PAMS standard method, i.e., NIEA A505.12B. The precision test showed a relative standard deviation (RSD) of 1% to 4.6%, well below the method’s requirement of 25%. The accuracy test results demonstrated the recovery of 84.48% to 122.74%, withing the method’s criteria of 75% to 125%. When comparing the developed system with a commercial counterpart used at PAMS stations, 90% of the peaks showed improved separation, and all peaks displayed less tailing in chromatography.
Water vapor in the environment greatly affects the sensitivity of the mass spectrometer, leading to a rapid decrease in ion source sensitivity, increased maintenance costs, and inconsistent results. In this study, we demonstrate that moisture is the key factor affecting ion source sensitivity by varying the humidity of the sample and introducing four internal standards (Bromochloromethane, 1,4-Difluorobenzene, Chlorobenzene-d5, and p-Bromofluorobenzene) to evaluate the impact on ion source sensitivity. Internal standards allow for mass spectrometry calibration and direct monitoring of ion source stability. After 70 consecutive injections with dry gas, the peak areas of the four internal standards only changed by 3.7% on average. In contrast, after the 70th test with humid gas, the peak areas of the internal standard decreased to 55.10%, demonstrating the significant impact of moisture on the ion source’s sensitivity.
For environmental monitoring, we replaced regular capillary columns with low-bleed columns. These low-bleed columns, which feature low backpressure and thicker films, reduce the likelihood of stationary phase material being carried into the detector, thereby minimizing ion source contamination and maintaining sensitivity. Results showed that after testing with low-bleed columns, the internal standard area decreased to 47.49%, compared to only 8.55% left with regular columns. This result demonstrates how the properties of stationary phase can affect ion source sensitivity. Using low-bleed columns can effectively counteract the impact of water vapor on the ion source sensitivity, prolonging the service life of the ion source. Ultimately, this increases the stability and longevity of the monitoring instruments and reduces the overall maintenance costs. |
參考文獻 |
1. Hahad, O., et al., Ambient air pollution increases the risk of cerebrovascular and neuropsychiatric disorders through induction of inflammation and oxidative stress. International journal of molecular sciences, 2020. 21(12): p. 4306.
2. Cohen, A.J., et al., Estimates and 25-year trends of the global burden of disease attributable to ambient air pollution: an analysis of data from the Global Burden of Diseases Study 2015. The lancet, 2017. 389(10082): p. 1907-1918.
3. Chen, S.-P., et al., Taiwan ozone trend in response to reduced domestic precursors and perennial transboundary influence. Environmental Pollution, 2021. 289: p. 117883.
4. World Health Organization, Inter-Organization Programme for the Sound Management of Chemicals, Principles for modelling dose-response for the risk assessment of chemicals. Vol. 239. 2009: World Health Organization.
5. Popp, D., Pollution control innovations and the Clean Air Act of 1990. Journal of Policy Analysis and Management, 2003. 22(4): p. 641-660.
6. Schmincke, H.-U. and H.-U. Schmincke, Volcanic hazards, volcanic catastrophes, and disaster mitigation. Volcanism, 2004: p. 229-258.
7. Guo, Y., et al., Recent advances in VOC elimination by catalytic oxidation technology onto various nanoparticles catalysts: a critical review. Applied Catalysis B: Environmental, 2021. 281: p. 119447.
8. Leikauf, G.D., Hazardous air pollutants and asthma. Environmental Health Perspectives, 2002. 110(suppl 4): p. 505-526.
9. Wang, F., et al., Effect of exposure to volatile organic compounds (VOCs) on airway inflammatory response in mice. The Journal of toxicological sciences, 2012. 37(4): p. 739-748.
10. Tang, X., et al., Complete oxidation of formaldehyde over Ag/MnOx–CeO2 catalysts. Chemical Engineering Journal, 2006. 118(1-2): p. 119-125.
11. Huang, B., et al., Chlorinated volatile organic compounds (Cl-VOCs) in environment—sources, potential human health impacts, and current remediation technologies. Environment international, 2014. 71: p. 118-138.
12. U.S. Environmental Protection Agency, Technical Overview of Volatile Organic Compounds. 2024.
13. Zhu, L., D. Shen, and K.H. Luo, A critical review on VOCs adsorption by different porous materials: Species, mechanisms and modification methods. Journal of hazardous materials, 2020. 389: p. 122102.
14. 中華民國 環境部 國家環境研究院. 揮發性有機物空氣污染管制及排放標準. Available from: https://law.moj.gov.tw/LawClass/LawAll.aspx?pcode=O0020030.
15. Ryerson, T., et al., Observations of ozone formation in power plant plumes and implications for ozone control strategies. Science, 2001. 292(5517): p. 719-723.
16. Yari, A.R., et al., Study of ground-level ozone and its health risk assessment in residents in Ahvaz City, Iran during 2013. Toxin reviews, 2016. 35(3-4): p. 201-206.
17. Jacobs, E.T., J.L. Burgess, and M.B. Abbott, The Donora smog revisited: 70 years after the event that inspired the clean air act. American journal of public health, 2018. 108(S2): p. S85-S88.
18. Agency, U.S.E.P., Compendium Method TO-17 Determination of Volatile Organic Compounds in Ambient Air Using Active Sampling Onto Sorbent Tubes 1999.
19. U.S., E.P.A., Compendium Method TO-15Determination Of Volatile Organic Compounds (VOCs) In Air Collected In Specially-Prepared Canisters And Analyzed By Gas Chromatography/ Mass Spectrometry (GC/MS). 1999.
20. Agency, U.S.E.P., Compendium Method TO-14A Determination Of Volatile Organic Compounds (VOCs) In Ambient Air Using Specially Prepared Canisters With Subsequent Analysis By Gas Chromatography 1999
21. 固定污染源空氣污染物危害影響評估暨消費性產品揮發性有機物管制推動計畫. 2014.
22. 行政院環境保護署, 固定污染源空氣污染防制費收費費率修正草案總說明. 2018.
23. 空氣品質監測網 光化測站. 2024; Available from: https://airtw.moenv.gov.tw/CHT/TaskMonitoring/Photochemical/PhotochemicalIntro.aspx.
24. 中華民國環境部, 空氣中揮發性有機化合物檢測方法-不銹鋼採樣筒/氣相層析質譜儀法. 2020.
25. Holm, T., Aspects of the mechanism of the flame ionization detector. Journal of Chromatography A, 1999. 842(1-2): p. 221-227.
26. 王美珠, 針對工業排放之污染性有機氣態物質開發連續監測技術, in 化學系. 2016, 國立中央大學.
27. 李冠均, 自製新型除水及熱脫附濃縮裝置用於GC/MS線上分析揮發性有機汙染物, in 化學系. 2020, 國立中央大學.
28. 楊雅宜, 線上熱脫附-氣相層析/質譜儀技術即時監測工業區空氣中有害揮發性有機化合物, in 化學系. 2022, 國立中央大學.
29. Korban, A., et al., The perspectives of ethanol usage as an internal standard for the quantification of volatile compounds in alcoholic products by GC‐MS. Journal of Mass Spectrometry, 2020. 55(3): p. e4493.
30. 交通部中央氣象署. 交通部中央氣象署氣候月平均相對濕度. 2024 2024/07/15 [cited 2024; Available from: https://www.cwa.gov.tw/V8/C/C/Statistics/monthlymean.html.
31. 朱晨瑄, 以線上熱脫附氣相層析質譜法監測空氣中有害空氣污染物, in 化學系. 2020, 國立中央大學.
32. 林宥辰, 開發氣相層析心切技術分析空氣中有害揮發性有機化合物, in 化學系. 2023, 國立中央大學.
33. Deans, D.R., A new technique for heart cutting in gas chromatography [1]. Chromatographia, 1968. 1(1): p. 18-22.
34. C. Ruhle, G.T.E., S. Urban, J.P. Dufour, P.D. Morrison, P.J. Marriott, Multiple component isolation in preparative multidimensional gas chromatography with characterisation by mass spectrometry and nuclear magnetic resonance spectroscopy. J. Chromatogr. A, 2009. 1216: p. 5740-5747.
35. C.P.G. Ruhle, J.N., P.D. Morrison, R.C. Jones, T. Caradoc-Davies, A.J. Canty, M.G. Gardiner, V.A. Tolhurst, P.J. Marriott, Characterization of tetra-aryl benzene isomers by using preparative gas chromatography with mass spectrometry, nuclear magnetic resonance spectroscopy, and x-ray crystallographic methods. Anal. Chem, 2010. 82: p. 4501-4509.
36. D. Sciarrone, S.P., C. Ragonese, P.Q. Tranchida, P. Dugo, L. Mondello, Increasing the isolated quantities and purities of volatile compounds by using a triple Deans-switch multidimensional preparative gas chromatographic system with an apolar-wax-ionic liquid stationary-phase combination. Anal. Chem, 2012. 84: p. 7092-7098.
37. G.T. Eyres, S.U., P.D. Morrison, P.J. Marriott, Application of microscale-preparative multidimensional gas chromatography with nuclear magnetic resonance spectroscopy for identification of pure methylnaphthalenes from crude oils. J. Chromatogr. A, 2008. 1215: p. 168-176.
38. N. Ochiai, K.S., Selectable one-dimensional or two-dimensional gas chromatography-olfactometry/mass spectrometry with preparative fraction collection for analysis of ultra-trace amounts of odor compounds. J. Chromatogr. A, 2011. 1218: p. 3180-3185.
39. John V. Seeley, N.J.M., Steven V. Bandurski, Stacy K. Seeley, and James D. McCurry, Microfluidic Deans Switch for Comprehensive Two-Dimensional Gas Chromatography. Anal. Chem, 2007. 79(5): p. 1840-1847.
40. Li, M.W.-H., et al., Microfabricated porous layer open tubular (PLOT) column. Lab on a Chip, 2019. 19(23): p. 3979-3987.
41. 中華民國環境部, NIEA-PA107 環境檢驗方法偵測極限測定指引. 2004.
42. Märk, T.D. and G.H. Dunn, Electron impact ionization. 2013: Springer Science & Business Media.
43. Siegel, J.A. and P.J. Saukko, Encyclopedia of forensic sciences. 2012: Academic Press.
44. Karasek, F.W. and R.E. Clement, Basic gas chromatography-mass spectrometry: principles and techniques. 2012: Elsevier.
45. Engewald, W., K. Dettmer-Wilde, and H. Rotzsche, Columns and stationary phases, in Practical Gas Chromatography: A Comprehensive Reference. 2014, Springer. p. 59-116.
46. Grob, K. and G. Grob, Capillary columns with immobilized stationary phases. Part 4: A moderately polar phase, OV‐1701. Journal of High Resolution Chromatography, 1982. 5(1): p. 13-18.
47. Grob, K. and G. Grob, Capiliary columns with immobilized stationary phases. Part 5: Determination of column bleeding; re‐silylation. Journal of High Resolution Chromatography, 1982. 5(7): p. 349-354.
48. Bakos, T., S. Rashkeev, and S. Pantelides, H 2 O and O 2 molecules in amorphous SiO 2: defect formation and annihilation mechanisms. Physical Review B, 2004. 69(19): p. 195206.
49. 呂秉祥, 自製除水及熱脫附儀串接氣相層析質譜儀用於連續監測大氣中有機污染物, in 化學系. 2022, 國立中央大學.
50. 施昱廷, 以氣相層析搭載電子捕捉偵測技術驗證自製前濃縮儀穩定性, in 化學系. 2023, 國立中央大學. |