Electrospray ionization source and method for mass spectrometric analysis

An improved electrospray ionization (ESI) system source and method is presented including an electrospray ionization source for introducing an ionized molecular sample into a mass spectrometer for analysis. The ESI source is constructed in the configuration of a probe that makes use of a standard 0.5 inch (13 mm) vacuum lock commonly found on conventional mass spectrometers. The ESI probe comprises a desolvation tube, a voltage source for applying a voltage to the desolvation tube, a resistance coil for heating the desolvation tube, a sensor for measuring the temperature of the desolvation tube, a skimmer positioned downstream of the desolvation tube for directing the ions to the lens stack of the mass spectrometer, a voltage source for applying a voltage to the skimmer, a spacer lens positioned upstream of the skimmer for focusing the ions prior to their entering the skimmer, and an evacuable dielectric encasement for housing the components of the probe assembly. This novel ESI source makes available a wealth of new analytical methods and applications that heretofore were unknown to the field, including novel data interpretations of ESI results and the ability to determine the process by which protein structures and functions may be modified by the attachment of small molecules to the protein surface, particularly crown ethers.