ELECTRON COLLISION-INDUCED DISSOCIATION FOR MASS SPECTRO

点击翻译按钮获取中文摘要

Our project is to develop, test and evaluate an electron beam technique for collision-induced dissociation for mass spectrometric identification and structure elucidation of compounds. At present, dissociation is primarily induced by collision of the mass selected beam ions with a gas target. We propose instead to use an electron beam to induce dissociation. The intense electron current required for efficient dissociation will be obtained from Spindt-type field emission cathodes, recently developed at SRI International. Important advantages of electron collision-induced dissociation (El CID) over the use of the gas target are: 1) The resultant dissociation pattern would be similar to that produced by electron ionization making the vast library of EI spectra available for identification purposes; 2) All mass spectrometers will produce similar dissociation patterns when using the same electron collision energy; 3) The electron beam could be switched rapidly, permitting the use of lock-in amplifier techniques; 4) Signal losses and resolution degradation caused by scattering and charge-exchange neutralization in the collision cell would be eliminated; 5) Dissociation efficiency should increase approximately linearly with mass; and 6) The electron gun would introduce no gas load to the mass spectrometer vacuum, be small in size and relatively inexpensive. These improvements should make the electron CID technique more practical and universally applicable for the analysis and structural elucidation of complex biological compounds.