Electrospray mass spectroscopy, mass spectroscopy of ions created by an electrospray process, should be significant for the study of nonvolatile substances such as high polymers or thermally unstable lower molecular weight species. Intact gas-phase macroions of polystyrene, polyvinylpyrrolidone, and lysozyme were prepared by this technique, and low -resolution M/z distributions were inferred from data obtained using a nozzle beam system with repeller-grid, Faraday-cage system as an analyzer-detector. Use of a time of flight mass spectrometer to improve resolution is not feasible, since the magnetic electron multipliers used to detect ions in TOF spectrometers have been shown to have negligible response to macroions. Applicability of the Flasma Chromatograph to determination of the charge states of gaseous macroions is also being investigated. /Currently available techniques of determining molecular weights and ^ molecular weight distributions permit only low-resolution analyses. Miiller ( 1 ) has recently stated "If we could determine molecular weights [of macromolecules] to a tenth of a percent or better, a load could be taken from the microanalysis' shoulders/' The primary ( although not the only) problem which has heretofore prevented the development of a mass spectrometer for use with macromolecules is that of producing intact gas-phase macroions. Owing to the low vapor pressures of macromole cules, macroions cannot be produced in the gas phase by conventional techniques without extensive degradation and/or fragmentation. Electro spray mass spectroscopy provides a solution to this basic problem.Electrospray mass spectroscopy ( EMS ) is the mass spectroscopy of gaseous ions produced by electrospraying into a suitable gas at atmos pheric pressure a dilute solution containing as solute the macromolecules in question. (Although the use of other gases is possible, we have ob tained our best results with nitrogen gas.) Although the technique is 73 Downloaded by NORTH CAROLINA STATE UNIV on October 24, 2012 |