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自動化溫室效應氣體分析系統 之建立與應用 1 Speaker : Ming-Xia Li Advisor : Prof. Jia-Lin Wang Construction of an automated GC system for measuring atmospheric greenhouse gases
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Introduction 2 GWP 100 : 1 364 ~ 408 ppm GWP 100 : 1 364 ~ 408 ppm GWP 100 : 298 303 ~ 326 ppb GWP 100 : 298 303 ~ 326 ppb GWP 100 : 25 1758 ~ 2133 ppb GWP 100 : 25 1758 ~ 2133 ppb
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Analytical Techniques 3
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4 Our analytical system Sampling system Sample automatically fills up to 700 torr Oven : 70 ℃
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5 Column Configuration CH 4 & CO 2 N2ON2O
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Injection 6 Back-Flush 6 Actions O 2, N 2 O, other compounds other compounds O 2, N 2 O other compounds Sampling O 2, N 2 O N2ON2OO2O2
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Channel switching 7 H2H2 Methanizer Composition : 30 ~ 50% NiO (nickel(II) oxide) and 50 ~ 70% SiO 2 Function : reduced CO 2 into CH 4 Temperature : 375°C CO 2 + 4H 2 → CH 4 + 2H 2 O CO 2 CH 4
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Chromatograms 8 CO 2 FID ECD N2ON2O O2O2 CH 4
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Experimental Carrier gases Oxygen cutting or not Parameter optimization 9
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Different carrier gases – N 2 vs. CH 4 /Ar 10 N2N2 CH 4 /Ar When the carrier gas uses 5% CH 4 /Ar, the single of N 2 O will increase N2ON2O
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Cutting oxygen or not 11 Not cut oxygen Cut oxygen When cut oxygen, the single of N 2 O just increase slightly, but the analyze time will increase N2ON2O O2O2
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Optimize the parameters 12
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Results and discussion Linearity Limit of Detection Reproducibility 13
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Connecting with Vacuum System 14 vacuum system When system connects with vacuum system, makes sure samples are not be contaminated.
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Quantitative – Working Standard 15 CO 2 CH 4 N2ON2O Standard15.316250.4 Standard concentrations1788 ppb10 ppm Working standard signal327616.03647.31 Working standard concentrations372.66 ppm1873 ppb398 ppb Calibration curve - CO 2 Using NOAA standards to make calibration curves
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Linearity 16 Pressure range : 4 ~ 44 psi
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Limits of Detection CO 2 CH 4 N2ON2O D.L. Concentration 3.42 ppm 364 ~ 408 ppm 138.34 ppb 1758 ~ 2133 ppb 2.30 ppb 303 ~ 326 ppb Reproducibility CO 2 CH 4 N2ON2O RSD0.96%0.86%0.45% 17 Based on 3 times standard deviation N = 7 Pressure : 4 psi Pressure : 10 psi
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18 Canister Analysis
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Canister sampling in Taipei area in 2012 Sampling time : 2012/02/14 05:00~06:00 am 18:00~19:00 pm 53 sampling sites Sampling time less than 1 min Monitoring compounds : CFCs, CO 2, CH 4, N 2 O, NMHCs Look for emissions hot spots – sources of GHGs. 19 Ref. Chemosphere 1998, Vol.36, No. 10, 2391-2400 Ref. Analytica Chimica Acta 2006, 576, 91-99
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20 Evening (18:00 ~ 19:00) Morning (05:00 ~ 06:00) CO 2 Concentration range : 387.04 ~ 578.12 ppmv
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21 Evening (18:00 ~ 19:00) Morning (05:00 ~ 06:00) CH 4 Concentration range : 1837.57 ~ 4496.74 ppbv
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22 Evening (18:00 ~ 19:00) Morning (05:00 ~ 06:00) N2ON2O N2ON2O Concentration range : 392.06 ~ 421.88 ppbv
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Conclusions The system measures CH 4 、 CO 2 、 N 2 O in 10 minutes for each sample. It has very good reproducibility (RSD < 1%), and linearity (R 2 = 0.9999). The limits of detection for CH 4 is 138.34 ppb (vs. ~1.7 ppm), CO 2 is 3.42 ppm (vs. >360 ppm), and N 2 O is 2.3 ppb (vs. >300 ppb). 23
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24 Thanks For Your Attention
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