Traditional ion trap mass spectrometry which utilize internal ionization could not perform negative ion analysis. However, since 1996, the first commercial ion trap mass spectrometer with an external ionization source(Finnigan GCQ) allows operating at higher pressure for the source region and also a modification detector with the changeable dynode (.plmin.15KV). Therefore, it can be applied to perform negative ion analysis. In our hands, we first applied this benchtop ion trap to characterize an array of uracil compounds and their derivatives by negative ion analysis. Methane was used as the reagent gas. Beside, the CAD (Collisionally activated dissociation) technique was applied to perform structural information. From the experimental results, we found that this series of compounds can eliminate one molecule of HNCO typically. In addition, Formation of the dimer ions (2M- H)/sup -/ and their fragment ions could be observed too. The relationship between the structural difference with their reactivity will be discussed in great details.
第七屆分析化學技術交流研討會暨一九九九台北國際分析化學研討會會後會:研討會會程與論文摘要=7th Annual Conference for Technical Communication on Analytical Chemistry and 1999 International Chemical Conference, Taipei: Analytical Chemistry--Post Conference: Final Program & Abstract Book