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dc.contributor.authorChen, Xiaonan.en_US
dc.date.accessioned2009-06-15T17:00:48Z
dc.date.available2009-06-15T17:00:48Z
dc.date.issued2005-06-15T17:00:48Z
dc.identifier.urihttp://hdl.handle.net/10464/1633
dc.description.abstractAn efficient way of synthesizing the deuterium labelled analogues of three methoxypyrazine compounds: 2-d3-methoxy-3-isopropylpyrazine, 2-d3-methoxy-3- isobutylpyrazine, and 2-d3-methoxy-3-secbutylpyrazine, has been developed. To confirm that the deuterium labels had been incorporated into the expected positions in the molecules synthesized, the relevant characterization by NMR, HRMS and GC/MS analysis was conducted. Another part of this work involved quantitative determination of methoxypyrazines in water and wines. Solid-phase extraction (SPE) proved to be a suitable means for the sample separation and concentration prior to GC/MS analysis.Such factors as the presence of ethanol, salt, and acid have been investigated which can influence the recovery by SPE for the pyrazines from the water matrix. Significantly, in this work comparatively simple fractional distillation was attempted to replace the conventional steam distillation for pre-concentrating a sample with a relatively large volume prior to SPE. Finally, a real wine sample spiked with the relevant isotope-labelled methoxypyrazines was quantitatively analyzed, revealing that the wine with 10 beetles per litre contained 138 ppt of 2-methoxy-3-isopropylpyrazine. Interestingly, we have also found that 2-methoxy-3-secbutylpyrazine exhibits an extremely low detection limit in GC/MS analysis compared with the detection limit of the other two methoxypyrazines: 2- methoxy-3-isopropylpyrazine and 2-methoxy-3-isobutylpyrazine.en_US
dc.language.isoengen_US
dc.publisherBrock Universityen_US
dc.subjectOrganic compoundsen_US
dc.subjectOrganic compoundsen_US
dc.subjectMass spectrometry.en_US
dc.subjectSpectrum analysis.en_US
dc.titleSynthesis of isotope-labelled methoxypyrazine compounds as internal standards and quantitative determination of aroma methoxypyrazines in water and wines by solid-phase extraction with isotope dilution-GC-MS /en_US
dc.typeElectronic Thesis or Dissertationen_US
dc.degree.nameM.Sc. Chemistryen_US
dc.degree.levelMastersen_US
dc.contributor.departmentDepartment of Chemistryen_US
dc.degree.disciplineFaculty of Mathematics and Scienceen_US


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