APPLICATION OF HIGH PERFORMANCE ION CYCLOTRON RESONANCE MASS SPECTROMETRY AND COMPUTER PATTERN RECOGNITION TO THE STUDY OF LOW PRESSURE METAL ION CHEMICAL IONIZATION REAGENTS (INSTRUMENTATION, CHEMOMETRICS, LASER IONIZATION).

摘要

A high performance ion cyclotron resonance (ICR) mass spectrometer has been designed and constructed for the study of metal ion reactions in the gas phase. This ICR instrument employs a frequency-swept capacitance bridge detection circuit operated in conjunction with a modified single region trapped ion cell. Although several similar detector circuits have been developed by other workers in recent years, our circuit offers a wider linear frequency bandwidth and a more versatile design than the others. When operated at a constant magnetic field strength of 1 tesla, the mass range of this ICR extends from 15-1000 atomic mass units. As with other instruments of this type, high resolution can be obtained under low pressure conditions, with a resolution of > 50,000 having been demonstrated with Fe('+) at mass 56.; Gas phase ion-molecule reactions of Sc('+) and Y('+) with alkanes, alkenes, aldehydes, ketones, ethers and alcohols were investigated by ICR and FTMS. Both of these metal ions display an unusually high degree of reactivity towards organics, activating C-H and C-C bonds in hydrocarbons as well as C-O bonds in oxygenated compounds. These two metal ions also generate an abundance of dialkyl-metal complexes when they are reacted with linear and branched alkanes. This type of behavior has not been observed with other transition metals.; Finally, computer pattern recognition has been applied to the interpretation of the metal ion ICR spectra and has demonstrated that transition metal ions may be useful as selective chamical ionization reagents for mass spectrometry.