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指導教授：徐永源博士 報告者：曾培芬 學號： M9681322

Analysis of semi-volatile organic compounds in aqueous samples by microwave-assisted headspace solid-phase microextraction coupled with gas chromatography-electron capture detection. Yaping Huang, Yu-Chuan Yang, Youn Yuen Shu*. 指導教授：徐永源博士 報告者：曾培芬 學號： M9681322.

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指導教授：徐永源博士 報告者：曾培芬 學號： M9681322

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  1. Analysis of semi-volatile organic compounds in aqueous samples by microwave-assisted headspace solid-phase microextraction coupled with gas chromatography-electron capture detection Yaping Huang, Yu-Chuan Yang, Youn Yuen Shu* 指導教授：徐永源博士 報告者：曾培芬 學號：M9681322 ~Journal of Chromatography A,1140(2007)35-43

  2. Introduction ◆ Sample pretreatment technology ◆ Liquid-liquid extraction (LLE) ● Drawback large amount of organic solvent time consuming labor intensive ◆ Solid-phase extraction (SPE) ● Advantage small amount of solvent relatively ● Drawback plugging channeling large sample size used

  3. Introduction ◆ Solid-phase microextraction (SPME) ● first developed by Pawliszyn ● solvent free ● performed in two ways: -Direct immersion (DI-SPME) -Headspace (HS-SPME) ●Compare DI-SPME : influenced by sample matrix HS-SPME : reduce matrix interference for volatile compounds long sampling time relatively

  4. Introduction ◆Sample matrix heating before HS-SPEM ●water bath (WB) -slow and inefficient ●microwave-assisted (MA) -instantaneous localized superheating

  5. Introduction ◆ MA-HS-SPME ● Advantage -quick -solvent-less -temperature monitoring (equipped with infrared sensor) -very good linearity and sensitivity

  6. Introduction ◆MA-HS-SPEM coupled with GC-ECD -Analysis of semi-volatile organic compounds ◆Experimental purpose -Comparison WB-HS-SPME and MA-HS-SPEM -The optimum conditions for obtaining extraction efficiency -Application to the real sample

  7. Experimental ◆ Reagents and materials ● 1,2-Dichlorobenzene（1,2DCB） ● 1,3-Dichlorobenzene（1,3DCB） ● 1,4-Dichlorobenzene（1,4DCB） ● 2,4-Dinitrotoluene（2,4DNT） ● 2,6-Dinitrotoluene（2,6DNT ） ● 1,2,4-Trichlorobenzene（1,2,4TCB） ● Nitrobenzene（NB） ● Hexachlorobenzene（HCB） ● Hexachloro-1,3-butadiene （HCBD） ◆Internal standards: ．1,3,5-TCB ．1,2,3,4-TeCB

  8. Experimental SPME fiber:65μm PDMS-DVB（conditioned by GC injector under N2 stream for 1 hr at 250℃）

  9. Experimental • GC-ECD -Capillary column：HP-5, 30m×0.25mm I.D×0.5μm -The column was programmed as : 65℃(4min) →5 ℃/min to 80 ℃(2min) →10℃/min to 120 ℃(2min) →10 ℃/min to 270 ℃(5min) -Injector port : splitless -ECD:300 ℃ -Carrier gas: N2 ,flow-rate:0.7ml/min

  10. Results and discussion • Optimization of PDMS-DVB fiber desorption conditions in GC injection port -3min desorption time -at 250℃ -the fiber depth of 4.0cm -another 5 min desorption time

  11. Results and discussion ◆Optimization of MA-HS-SPEM and WB-HS-SPEM procedure ●Extraction time ●Temperature ●Effect of sample to headspace volume ratio ●Addition of sodium

  12. Extraction time Better!! MA-HS-SPEM WB-HS-SPEM 40min 30min

  13. Temperature MA-HS-SPEM WB-HS-SPEM 2,6DNT HCB

  14. Effect of sample to headspace volume ratio MA-HS-SPEM WB-HS-SPEM 20/20

  15. Addition of NaCl MA-HS-SPEM WB-HS-SPEM NB NB 2,4-DNT 2,4-DNT 2,6-DNT 2,6-DNT

  16. Results and discussion ◆Comparison of MA-HS-SPME and WB-HS-SPME

  17. Results and discussion ◆Validation of the MA-HS SPEM method --Correlation coefficient greater than 0.997

  18. Results and discussion ◆Application to the real sample -sample collected from university campus and Jen-Ai river

  19. Results and discussion Standard solution Artificial solution

  20. Results and discussion HCB 2,6-DNT HCDB 1,2,4-TBC River sample 2,4-DNT 2,6-DNT Campus sample HCB HCDB 1,2,4-TBC

  21. Conclusion • The optimum conditions: -30W microwave power for 30min at 70℃ -20ml aqueous sample in 40ml headspace -no addition of sodium • MA-HS-SPEM coupled with GC-EDC technique -acceptable accuracy -precision -wide-rang linearity -high sensitivity with detection limits at ng/L level in the analysis of water samples. • The microwave-assisted technique -viable -better extraction efficiency than conventional heating . • This method -fast, simple, low-cost, hazardous organic solvent free

  22. Thanks for your listening

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