Electrospray ionization diagram

Schematic diagram of an orthogonal Q/TOF instrument. In this example, an ion beam is produced by electrospray ionization. The solution can be an effluent from a liquid chromatography column or simply a solution of an analyte. The sampling cone and the skimmer help to separate analyte ions from solvent, The RF hexapoles cannot separate ions according to m/z values and are instead used to help confine the ions into a narrow beam. The quadrupole can be made to operate in two modes. In one (wide band-pass mode), all of the ion beam passes through. In the other (narrow band-pass mode), only ions selected according to m/z value are allowed through. In narrow band-pass mode, the gas pressure in the middle hexapole is increased so that ions selected in the quadrupole are caused to fragment following collisions with gas molecules. In both modes, the TOF analyzer is used to produce the final mass spectrum.

Fig. 13.1 A schematic simplification of typical events that occur during the formation of gas-phase ions by electrospray ionization. The diagram is loosely based upon those found elsewhere [1 b,c, 12].

Fig. 8. Schematic diagram of the desorption electrospray ionization (DESI) source. Reproduced with permission from Cotte-Rodriguez et al. [14]. Copyright 2005 American Chemical Society.

Figure 4.11. Schematic diagram of an LC/MS electrospray ionization (ESI) interface showing the nebulization of the LC eluent into droplets, evaporation of the solvent, and the ionization of the analytes, which are pulled inside the MS. Diagram courtesy of Agilent Corporation.

Mass spectrometry with its excellent sensitivity is emerging as one of the most powerful analytical techniques.16 Its importance was recognized by the awarding of the 2002 Nobel Prize in Chemistry to John B. Fenn and Koichi Tanaka for their research in mass spectrometric methods for biomolecules. The primary difficulties of combining LC and MS have been the interface, and the ionization of analytes in a stream of condensed liquids and transfer of ions into the high vacuum inside the mass spectrometry. Two common LC/MS interfaces are the electrospray ionization (ESI) and the atmospheric pressure chemical ionization (APCI). Figure 4.13a shows a schematic diagram of an... 

Fig. 24. Schematic diagram outlining the experiment designed to monitor hydrogen exchange in the GroEL [3SS] BLA complex (BLA = bovine a-lactalbumin) by electrospray ionization mass spectrometry (ESI-MS). Before formation of the complex, all exchangeable sites in a-lactalbumin were deuterated by incubation of the apoprotein in D2O. Hydrogen exchange is initiated by a 10-fold dilution of the complex in H2O, pH...

Figure 9.5. Schematic diagram of the Agilent orthogonal electrospray ionization source for LC-MS. (From ref. [29] Elsevier)...

Figure 9.10. Schematic diagram of a packed column SFC-MS interface with electrospray ionization. This interface features a liquid pressure-regulating flow for pressure control to just before the expansion region. (From ref. [75] Elsevier).

Figure 35.12 shows a schematic diagram of an online high-throughput detection system for a reaction product synthesized by a microreactor. The system has a synthesis chip that a microreactor for the synthesis of 2,2,2-trifluore-A-phenetyl acetamide (TPA), an extraction chip for the purification of TPA from the reaction mixture, and an electrospray ionization mass spectrometer (ESl-MS) for... 

FIGURE 9.2 Schematic diagram of electrospray ionization-ion trap-low-pressure ion mobility spectrometer-time-of-flight mass spectrometer (ESI-IT-IMS-TOF). (From Henderson et al., ESI/ion trap/ion mobility/time-of-flight mass spectrometry for rapid and sensitive analysis of biomolecular mixtures, Anal. Chem. 1999,71,291. With permission.)... 

Figure 2.18. Block diagram of an electrospray ionization source that uses skimmer lenses. (Reproduced from C. Dass, Principles and Practice of Biological Mass Spectrometry, Wiley-Interscience, 2001.)...

Hgure 4 Schematic diagram of the experimental setup for the study of matrix ion-suppression effects in electrospray ionization mass spectrometry. (Based on Bonfiglio R et at. (1999) Rapid Communications in Mass Spectrometry 13 1175.)... 

All mass spectrometers require a sample input system, an ionization source, a mass analyzer, and a detector. All of the components with the exception of some sample input systems or ion source volumes are under vacuum (10" -10" torr for that portion where ions are separated by mass, i.e., the analyzer, or 10 -10" torr in some ion sources, where the ions are initially formed), so vacuum pumps of various types are required. Other ion sources, such as the direct analysis in real time (DART) (discussed in Section 9.2.23), electrospray ionization (ESI) (Sections 9.2.2.3 and 13.1.6.1), or chemical ionization (Cl) (Section 9.2.2.2), operate at atmospheric pressure and use extraction lenses set to a polarity opposite that of the ions to draw them into subsequent stages of the MS instrument. Modern mass spectrometers have all of the components under computer control, with a computer-based data acquisition and processing system. A block diagram of a typical mass spectrometer is shown in Figure 9.4. 

FIGURE 1 Diagram of the capillary HPLC configuration as attached to the electrospray ionization mass spectrometer. Flow through the 320- m-i.d. packed capillary columns is adjusted to 4 1 per minute. 

Fig. 7.6 Schematic diagram of the setup and ion source for desorption electrospray ionization (DESI-MS). (Adapted from N. Talaty et al. Analyst, 130, 2005, 1624-1633 with permission of the PCCP Owner Societies)...

Like DART, DESI has received widespread acceptance as evidenced by more than 750 papers and conference presentations till mid-2014, referring to the technique since its introduction in 2004 by Cooks and coworkers [195, 196]. The technique makes use of electrospray ionization (ESI) that is widely used in the mass spec-trometiy of larger molecules in which a solution is nebulized to create a fine spray of very small droplets. In DESI, a standard electrospray of charged droplets hits the surface where the molecules of interest are present or adsorbed (including larger biomolecules), detaches them from the siuface, and delivers them as desolvated ions in the mass spectrometer. DESI is thus similar to DART (Sect. 8.4) where the gaseous plasma of ions from the ion source desorbs molecules from a surface. A schematic diagram of the main aspects of a DESI ion source is shown in Fig. 8.9. 

Fig. 7-59. Schematic diagram of the ionization process in electrospray ionization ( ionSpray , Perkin-Elmer Sciex).

Schematic diagram of the principle of electrospray ionization in the positive-ion...

Figure 2.9 Schematic diagram of desorption electrospray ionization source. The letters a, P, and d represent the spray impact angle, desorbed ions collection angle, and the distance between spray tip and the surface, respectively.

Figure 3 A schematic diagram of an orthogonal-injection TOF instrument with an electrospray ionization source. Collisional cooling is used in a quadrupole ion guide to produce a beam with a small energy spread, and a small cross section. The pressure in the ion guide is typically tens of millitorr the main TOF chamber is under high vacuum, typically torr. Ions are pulsed into...

Figure 32F-1 Block diagram of an LC/MS system. The effluent from the LC column is introduced to an atmospheric pressure ionization source, such as an electrospray or chemical ionization. The ions produced are sorted by the mass analyzer and detected by the ion detector.

A block diagram of the main components of a mass spectrometer is presented in Figure 9.1. Individual stable compounds, and possibly simple mixtures, are conventionally introduced into the ion source by a heated direct inlet probe for liquids and solids, or by a vacuum leak for volatile liquids and gases [1-7]. Thermally labile and ionic compounds, and some polar compounds, in solution are introduced by a continuous infusion mechanism, and ionized by one of the soft ionization techniques, such as electrospray. For mixtures, in general, a chromatographic sample inlet is the preferred choice. 

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