四極柱質譜儀第三穩定區的頻率掃描與絕對電荷分析程式

Abstract

I. 現今大多數的四極柱質譜儀，幾乎都是以電壓掃描的方式來作質譜掃描，其頻率約在1MHz左右，而當掃描的質量範圍越來越大，所需要的掃描電壓也越來越大，若是用頻率掃描的方式而言，對於大的質量範圍，所需要的掃描頻率則越小，而在電路設計上，降低掃描頻率是比增加掃描電壓容易的，操作上也較安全，本實驗的目的，是嘗試將四極柱質譜儀，以頻率掃描的方式來操作，而達成大分子的質譜掃描，在儀器設備方面，離子源採用電灑游離法產生離子，電路設備頻率範圍為400~100 kHz，交流電壓約100~200伏特，樣品採用蛋白質gramicidin S，對於此蛋白質正兩價離子，質荷比為570.5，質譜解晰度最高可達到約200。實驗結果並與電腦模擬做一對照。由實驗結果看來，若是未來能設計高電壓及高頻率的電源供應器，頻率掃描的四極柱質譜儀能有其發展空間。 II. 光探測法之單粒子質譜儀，是將帶電粒子捕捉在四極離子阱中，利用電子槍改變粒子的質荷比，被捕捉粒子的質荷比，可由調整帶電粒子的穩定態軌跡求得，電壓與頻率二者是實驗的控制參數，粒子絕對質量的決定，是設定一組電荷數去尋找對應的一組質量解，粒子質量的最小標準差作為最佳質量解的依據，我撰寫二個電腦程式以加快資料分析的速度及正確性。

Part A: A linear quadrupole mass spectrometer operating in the third stability region [(a, q) ≈ (3, 3)] has been developed and utilized to obtain the mass spectra of multiply charged protein ions generated by electrospray ionization. The spectra were acquired by scanning the frequency of the quadrupole with a home-built wide-band power amplifier from 400 to 100 kHz at constant voltage amplitudes in the range of 100 V. A resolution approaching R1/2 = 200 was achieved for doubly charged gramicidin S ions at m/z 570.5. Besides the experiments, a computer simulation was utilized to discuss the results of experiments. Further improvement of the mass resolution is expected when a higher voltage power amplifier is used. Part B: A new technique for determining the masses of nanoparticles in a quadrupole ion trap has been developed in our group. When a particle is introduced into the ion trap and trapped, mass-to-charge ratio of the particle is determined by varying the voltage and RF frequency. Computer programs were utilized to speed the data analysis. Two kinds of programs were compared to testify the validity of data analysis.