Electrospray ion source: another variation on the free-jet theme
01 Sep 1984-The Journal of Physical Chemistry (American Chemical Society)-Vol. 88, Iss: 20, pp 4451-4459
TL;DR: In this paper, a small capillary at 2-10 kV relative to ground is electrosprayed into a bath gas to form a gaseous dispersion of ions that is expanded into vacuum in a small supersonic free jet.
Abstract: Solutions passed through a small capillary at 2-10 kV relative to ground are electrosprayed into a bath gas to form a gaseous dispersion of ions that is expanded into vacuum in a small supersonic free jet A portion of the jet is passed through a skimmer to form a molecular beam that contains a variety of ionic species Mass spectrometric analysis reveals that these species include solute cations in aggregation with solvent molecules and/or nonionized solute species The nature of the product ions depends upon the composition and feed rate of the original solution, the temperature and composition of the bath gas, and the voltage applied to the capillary The exploratory experiments reported here suggest that this novel ion source may be useful for producing in vacuo a wide variety of cluster ions for examination by various spectroscopic techniques Also inviting is the prospect of extending the applicability of mass spectrometric analysis to large organic molecules that are too complex, too fragile, or too nonvolatile for ionization by more conventional methods Another intriguing possibility is to use the technique on probing the microscopic structure and properties of solutions
Citations
More filters
TL;DR: Spectra have been obtained for biopolymers including oligonucleotides and proteins, the latter having molecular weights up to 130,000, with as yet no evidence of an upper limit.
Abstract: Electrospray ionization has recently emerged as a powerful technique for producing intact ions in vacuo from large and complex species in solution. To an extent greater than has previously been possible with the more familiar "soft" ionization methods, this technique makes the power and elegance of mass spectrometric analysis applicable to the large and fragile polar molecules that play such vital roles in biological systems. The distinguishing features of electrospray spectra for large molecules are coherent sequences of peaks whose component ions are multiply charged, the ions of each peak differing by one charge from those of adjacent neighbors in the sequence. Spectra have been obtained for biopolymers including oligonucleotides and proteins, the latter having molecular weights up to 130,000, with as yet no evidence of an upper limit.
6,765 citations
TL;DR: A novel procedure in which a very small disk of beads embedded in a Teflon meshwork is placed as a microcolumn into pipet tips, finding that the Stage system is well-suited as a universal sample preparation system for proteomics.
Abstract: Proteomics is critically dependent on optimal sample preparation. Particularly, the interface between protein digestion and mass spectrometric analysis has a large influence on the overall quality and sensitivity of the analysis. We here describe a novel procedure in which a very small disk of beads embedded in a Teflon meshwork is placed as a microcolumn into pipet tips. Termed Stage, for STop And Go Extraction, the procedure has been implemented with commercially available material (C18 Empore Disks (3M, Minneapolis, MN)) as frit and separation material. The disk is introduced in a simple and fast process yielding a convenient and completely reliable procedure for the production of self-packed microcolumns in pipet tips. It is held in place free of obstacles solely by the narrowing tip, ensuring optimized loading and elution of analytes. Five disks are conveniently placed in 1 min, adding 300 μL/...
2,358 citations
TL;DR: Electrospray (E S ) ionization has recently shown itself capable of producing intact ions, with multiple charges, from remarkably large, complex, and fragile parent species as mentioned in this paper, which is the state-of-the-art in mass spectrometric analysis.
Abstract: Chemistry has its origins as a quantitative science in the careful weighing of products and reactants by Lavoisier and his followers beginning some 200 years ago. Ever since then, the constantly evolving gravimetric balance has been a faithful servant of the laboratory chemist and has played a major role in developing the analytical methods that are the foundation of contemporary chemical science. Perhaps the ultimate stage in the evolution of that balance is represented by the modern mass spectrometer. It is able to determine with high precision the masses of individual atoms and molecules by transforming them into ions and measuring the response of their trajectories in vacuo to various combinations of electric and magnetic fields. Clearly, the sine qua non of such mass determination is the transformation of analyte atoms and molecules from their initial state in a sample to ions in vacuo ready for ”weighing.” Over the years, ingenious investigators have produced a variety of methods for achieving this transformation. One of them, electrospray ( E S ) ionization, has recently shown itself capable of producing intact ions, with multiple charges, from remarkably large, complex, and fragile parent species. Our assignment here is to review what has thus far been learned about this still uncommon technique and what it seems able to offer practitioners of mass spectrometric analysis. Our approach will be to set forth the present state of the ES ionization art in terms of a sort of menu of its procedures, processes, performance, and promise. Until very recently we have been almost the only group that has worked with ES ionization since the pioneering efforts of Malcolm Dole (1) some 20 years ago. Consequently, this review is more tutorial than most. Moreover, it may seem like a cook book that is overly preoccupied with the authors’ own culinary adventures. The reasoil is that many of the dishes to be described were first tried out in our own kitchen. Therefore, we earnestly urge the reader to remember what every gourmet knows: the piquancy of any dish on a bill of fare is due much less to its ingredients than to the skill of the chef whc. prepares it.
1,487 citations
TL;DR: L'effluent de chromatographie en phase liquide projete electrostatiquement dans un bain de gaz froid cree une dispersion de gouttelettes chargees qui s'evapore rapidement.
Abstract: L'effluent de chromatographie en phase liquide projete electrostatiquement dans un bain de gaz froid cree une dispersion de gouttelettes chargees qui s'evapore rapidement. Lorsque les gouttelettes deviennent plus petites, l'augmentation de la densite de charge superficielle et la baisse du rayon de courbure creent un champ suffisamment fort pour desorber les ions du solute. Une partie passe a travers un canal et forme un jet libre supersonique, puis passera dans l'analyseur de masse
1,476 citations
TL;DR: Fundamental considerations suggest even more impressive developments may be anticipated related to detection sensitivity and methods for obtaining structural information, as well as new developments related to ESI-MS.
Abstract: The principles, development, and recent application of electrospray ionization-mass spectrometry (ESI-MS) to biological compounds are reviewed. ESI-MS methods now allow determination of accurate molecular weights for proteins extending to over 50,000, and in some cases well over 100,000. Similar capabilities are being developed for oligonucleotides. The instrumentation used for ESI-MS is briefly described and it is shown that, although ionization efficiency appears to be uniformly high, detector sensitivity may be directly correlated with molecular weight. The use of tandem mass spectrometry (e.g., MS/MS) for extending collision-induced dissociation (CID) methods to the structural studies of large molecules is described. For example, effective CID of various albumin species (molecular weight approximately 66,000) can be obtained, far larger than obtainable for singly charged molecular ions. The combination of capillary electrophoresis, in both free solution zone electrophoresis and isotachophoresis formats, as well as microcolumn liquid chromatography with ESI-MS, provides the capability for on-line separation and analysis of subpicomole quantities of proteins. These and other new developments related to ESI-MS are illustrated by a range of examples. Fundamental considerations suggest even more impressive developments may be anticipated related to detection sensitivity and methods for obtaining structural information.
1,041 citations