Probe electrospray ionization

The ionization methods reported for IMS included MALDI [41,76-80], Secondary Ion Mass Spectrometry (SIMS) [19, 81-86], Matrix-enhanced (ME)-SIMS [87, 88], Desorption Electrospray Ionization (DESI) [89-99], Nanostructure Initiator Mass Spectrometry (NIMS) [100-102], Atmospheric Pressure Infrared MALDI Mass Spectrometry (AP-IR-MALDI-MS) [103], Laser Ablation-inductively Coupled Plasma-Mass Spectrometry (LA-ICP-MS) [104-106], Laser Desorption Postionization (LDPI) [107], Laser Ablation Electrospray Ionization Mass Spectrometry (LAESI) [108, 109], and Surface-assisted Laser Desorption/ioniza-tion Mass Spectrometry (SALDI) [110-112], Another method was called probe electrospray ionization (PESI) that was used for both liquid solution and the direct sampling on wet samples. 

Yu, Z., Chen, L.C., Erra-Balsells, R., Nonami, H., Hiraoka, K. (2010) Real-time Reaction Monitoring by Probe Electrospray Ionization Mass Spectrometry. Rapid Commun. Mass Spectrom. 24 1507-1513. 

Probe electrospray ionization (PESI) and TOF-MS were used for direct profiling of phytochemicals in different parts of a fresh tulip bulb [80], which emphasized the possibility of conducting in-vivo MS analysis of less sensitive biological matrices such as plant tissues. Recently, Pan et al. [81] demonstrated single-probe MS which can conduct metabolomic analysis of individual living cells in real time. The diameter of this probe is < 10 pm which makes the device compatible with eukaryotic cells. Atmospheric pressure ion sources are particularly suitable for analysis of live biological specimens. Cellular metabolism does not need to be quenched before analysis. For instance, in laser ablation electrospray ionization (LAESI)-MS, cells are irradiated by a laser beam in order to extract small amounts of cytosolic components, and to transfer them to the ESI plume [82]. 

Ford, M.J., Deibel, M.A., Tomkins, B.A., Van Berkel, G.J. (2005) Quantitative thin-layer chromatography/ mass spectrometry analysis of caffeine using a surface sampling probe electrospray ionization tandem mass spectrometry system. Analytical Chemistry, 77, 4385-4389. 

Jensen, P. K., Pasa-Tolic, L., Anderson, G. A., Homer, J. A., Lipton, M. S., Bmce, J. E., and Smith, R. D. (1999). Probing proteomes using capillary isoelectric focusing-electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry. Anal. Chem. 71, 2076-2084. 

Loo, J. A. Loo, R. R. O. Udseth, H. R. Edmonds, C. G. Smith, R. D. Solvent-induced conformational-changes of polypeptides probed by electrospray-ionization mass-spectrometry. Rapid Comm. Mass Spectrom. 1991,5,101-105. 

DGE a AC AMS APCI API AP-MALDI APPI ASAP BIRD c CAD CE CF CF-FAB Cl CID cw CZE Da DAPCI DART DC DE DESI DIOS DTIMS EC ECD El ELDI EM ESI ETD eV f FAB FAIMS FD FI FT FTICR two-dimensional gel electrophoresis atto, 10 18 alternating current accelerator mass spectrometry atmospheric pressure chemical ionization atmospheric pressure ionization atmospheric pressure matrix-assisted laser desorption/ionization atmospheric pressure photoionization atmospheric-pressure solids analysis probe blackbody infrared radiative dissociation centi, 10-2 collision-activated dissociation capillary electrophoresis continuous flow continuous flow fast atom bombardment chemical ionization collision-induced dissociation continuous wave capillary zone electrophoresis dalton desorption atmospheric pressure chemical ionization direct analysis in real time direct current delayed extraction desorption electrospray ionization desorption/ionization on silicon drift tube ion mobility spectrometry electrochromatography electron capture dissociation electron ionization electrospray-assisted laser desorption/ionization electron multiplier electrospray ionization electron transfer dissociation electron volt femto, 1CT15 fast atom bombardment field asymmetric waveform ion mobility spectrometry field desorption field ionization Fourier transform Fourier transform ion cyclotron resonance... 

Electrospray ionization will often produce ions that are fully coordinated, stable, and nonreactive in the gas phase. These ions may be probed by removal of ligands to form coordinatively unsaturated ions that are generally reactive. The chemical activity of metal cluster ions differs markedly and often shows size specific enhanced reactivity or lack of reactivity. Silver cluster ions Ag are fairly inert similar to Ag+. Platinum cluster ions PL are quite reactive similar to Pt+. Often, large cluster ions only appear to react with one donor molecule such as benzene this may be due to low concentrations of reactants or short reaction times. Similar clusters may react with a larger number of smaller molecules, and so until more information is available, rules for the coordination behavior of metal clusters are as yet not available. 

If high-resolution measurements are performed in order to assign elemental compositions, internal mass calibration is almost always required. The calibration compound can be introduced from a second inlet system or be mixed with the analyte before the analysis. Mixing calibration compounds with the analyte requires some operational skills in order not to suppress the analyte by the reference or vice versa. Therefore, a separate inlet to introduce the calibration compound is advantageous. This can be achieved by introducing volatile standards such as PFK from a reference inlet system in electron ionization, by use of a dual-target probe in fast atom bombardment, or by use of a second sprayer in electrospray ionization. 

Katta, V., Chait, B. T. Conformational-changes in proteins probed by hydrogen-exchange electrospray-ionization mass-spectrometry. Rapid Commun Mass Spectrom 1991, 5, 214-217. 

Figure 14.5 Modified-ESI source for the direct infusion of undiluted ILs. A stainless steel wire is placed in the spray, leading to the optimal vaporization of the IL. Additionally, an orthogonal ESI source is used. Only a part of the IL ions is transferred into the MS, thus minimizing pollution of the source. (Modified from Dyson, R J. et al.. Direct probe electrospray (and nanospray) ionization mass spectrometry of neat ionic liquids. Chem. Commun., 2204, 2004. Reproduced by permission of the Royal Society of Chemistry.)...

Dyson, P. J. et al.. Direct probe electrospray (and nanospray) ionization mass spectrometry of neat ionic liquids. Chem. Commun., 2204, 2004. 

In direct introduction the sample can be introduced via a sample probe or plate through a vacuum lock, and can subsequently be ionized via El, Cl or matrix-assisted laser desorption ionization (MALDI see Section 2.4). Alternatively, the sample can be introduced as a liquid stream into an ion source at atmospheric pressure, after which it is subjected to electrospray ionization (ESI see Section 2.3). Direct injection does not offer any form of sample separation. 

Two-dimensional (2-D) crystallites are generally of a lower symmetry than 3-D crystals. The molecules in the 2-D crystallites cannot pack across a center of inversion as they most commonly do in 3-D. By applying modern analytical tools such as scanning tunneling and probe microscopy (STM, SPM), transmission electron microscopy (TEM), grazing incidence X-ray diffraction (GIXD), electrospray ionization (ESI) and matrix-assisted laser-... 

A new ionization method called desorption electrospray ionization (DESI) was described by Cooks and his co-workers in 2004 [86]. This direct probe exposure method based on ESI can be used on samples under ambient conditions with no preparation. The principle is illustrated in Figure 1.36. An ionized stream of solvent that is produced by an ESI source is sprayed on the surface of the analysed sample. The exact mechanism is not yet established, but it seems that the charged droplets and ions of solvent desorb and extract some sample material and bounce to the inlet capillary of an atmospheric pressure interface of a mass spectrometer. The fact is that samples of peptides or proteins produce multiply charged ions, strongly suggesting dissolution of the analyte in the charged droplet. Furthermore, the solution that is sprayed can be selected to optimize the signal or selectively to ionize particular compounds. 

Kujawinski, E. B., Del Vecchio, R., Blough, N. V., Klein, G. C., and Marshall, A. G. (2004). Probing molecular-level transformations of dissolved organic matter Insights on photochemical degradation and protozoan modification of DOM from electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry. Mar. Chem. 92, 23—37. 

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