DEVELOPMENT AND APPLICATIONS OF THE MAGIC LC/MS INTERFACE

The identification and quantification of involatile and/or thermally labile compounds in unknown samples presents a difficult challenge to the analytical chemist. The identification of these types of compounds may be accomplished using mass spectrometry in the electron impact (EI) ionization mode. The compounds must be pure when they enter the mass spectrometer however, and mixtures require a separation before analysis. The best separation method for thermally labile and involatile compounds is high performance liquid chromatography (HPLC). However, introduction of the column effluent into the ion source of the mass spectrometer results in a pressure that is too high to achieve EI ionization. An interface that can separate solute from solvent is therefore necessary if an EI spectrum is desired. The goal of this research project was to develop an LC/MS interface that would allow a choice of ionization techniques and chromatographic conditions and operate with adequate sensitivity for the analysis of environmental and biomedical samples. The name of the interface is the Monodisperse Aerosol Generation Interface Combining Liquid Chromatography with Mass Spectroscopy (MAGIC LC/MS).;The MAGIC LC/MS interface accomplishes solvent removal by three distinct processes, aerosol generation, aerosol desolvation and momentum separation. The effluent from the HPLC column is used to form an aerosol. The aerosol is desolvated leaving solute particles and solvent vapor. The solute is separated from the solvent by expansion through a supersonic nozzle. The center of the expanding beam is skimmed which results in solute enrichment because the solute particles are concentrated in the center of the beam. The enriched solute particle beam enters the ion source where the solute is vaporized and a mass spectrum is recorded.;The MAGIC interface was used for the successful analysis of several thermally labile and/or involatile compounds. The minimum detectable amount of analyte (MDA) using single ion monitoring is 100 pg. The full scan MDA is 10 ng. In general, for routine applications it is desirable to have 1 to 2 mg of analyte. Both EI and CI spectra can be readily obtained.