Mass spectrometry pressure ionization electrospray

HPLC-mass spectrometry (MS). MS conditions ionization mode, atmospheric pressure ionization-electrospray (API-ES) polarity, positive Vcap, 4000 V nebulizer pressure, 35 psig drying gas, 10 L min gas temperature, 350 °C fragmentor, 70 V scan range, 120-600 atm. 

In atmospheric pressure ionization sources (API) the ions are first formed at atmospheric pressure and then transferred into the vacuum. In addition, some API sources are capable of ionizing neutral molecules in solution or in the gas phase prior to ion transfer to the mass spectrometer. Because no liquid is introduced into the mass spectrometer these sources are particularly attractive for the coupling of liquid chromatography with mass spectrometry. Pneumatically assisted electrospray (ESI), atmospheric pressure chemical ionization (APCI) or atmospheric pressure photoionization (APPI) are the most widely used techniques. 

Liquid chromatography creates a huge volume of gas when solvent vaporizes at the interface between the column and the mass spectrometer.22 Most of this gas must be removed prior to ion separation. Nonvolatile mobile-phase additives (such as phosphate buffer), which are commonly used in chromatography, need to be avoided when using mass spectrometry. Pneumatically assisted electrospray and atmospheric pressure chemical ionization are dominant methods for introducing eluate from liquid chromatography into a mass spectrometer. 

Maurer, H. H. Kraemer, T. Ledvinka, O. Schmitt, C. J. Weber, A. A. 1997. Gas chromatography-mass spectrometry (GC-MS) and liquid chromatography-mass spectrometry (LC-MS) in toxicological analysis. Studies on the detection of clobenzorex and its metabolites within a systematic toxicological analysis procedure by GC-MS and by immunoassay and studies on the detection of alpha- and beta-amanitin in urine by atmospheric pressure ionization electrospray LC-MS. J. Chromatogr. B Biomed. Sci Appl., 689,81-89. 

See also Mass Spectrometry Overview Ionization Methods Overview Eiectron Impact and Chemical Ionization Atmospheric Pressure Ionization Techniques Electrospray Liquid Secondary Ion Mass Spectrometry Matrix-Assisted Laser Desorption/lonization Mass Separation Ion Traps Time-of-Flight. 

Albert, A., Engelhard, C. (2012) Characteristics of Low-temperature Plasma Ionization for Ambient Mass Spectrometry Compared to Electrospray Ionization and Atmospheric Pressure Chemical Ionization. Anal. Chem. 84 10657-10664. 

Siegel MW, Fite WL. Terminal ions in weak atmospheric plasmas. Applications of atmospheric pressure ionization to trace impurity analysis in gases. J Phys Chem. 1976 80 2871-81. Sunner J, Ikonomou MG, Kebarle P. Sensitivity enhancements obtained at high temperatures in atmospheric pressure ionization mass spectrometry. Anal Chem. 1988 60 1308-13. Thomson BA. Micro and nano-electrospray ionization techniques. In Gross M, Caprioli R, editors. Encyclopedia of mass spectrometry Vol6. Ionization methods. Oxford Elsevier, 2007. pp. 435 4. 

The advent of atmospheric-pressure ionization (API) provided a method of ionizing labile and nonvolatile substances so that they could be examined by mass spectrometry. API has become strongly linked to HPLC as a basis for ionizing the eluant on its way into the mass spectrometer, although it is also used as a stand-alone inlet for introduction of samples. API is important in thermospray, plasmaspray, and electrospray ionization (see Chapters 8 and 11). 

The term nebulizer is used generally as a description for any spraying device, such as the hair spray mentioned above. It is normally applied to any means of forming an aerosol spray in which a volume of liquid is broken into a mist of vapor and small droplets and possibly even solid matter. There is a variety of nebulizer designs for transporting a solution of analyte in droplet form to a plasma torch in ICP/MS and to the inlet/ionization sources used in electrospray and mass spectrometry (ES/MS) and atmospheric-pressure chemical ionization and mass spectrometry (APCI/MS). 

Electrospray ionization occurs by the same four steps as listed above for thermospray (see Section 4.6). In contrast to thermospray, and most other ionization methods nsed in mass spectrometry, it shonld be noted that electrospray ionization nnnsnally takes place at atmospheric pressure. A similar process carried out under vacuum is known as electrohydrodynamic ionization and gives rise to qnite different analytical results. This technique has not been developed into a commercial LC-MS interface and will not be considered further. 

Figure 5.1 Pesticides included in the systematic investigations on APCI-MS signal response dependence on eluent flow rate the parameter IsTow represents the distribution coefficient of the pesticide between n-octanol and water. Reprinted from J. Chromatogr, A, 937, Asperger, A., Efer, 1., Koal, T. and Engewald, W., On the signal response of various pesticides in electrospray and atmospheric pressure chemical ionization depending on the flow rate of eluent applied in liquid chromatography-mass spectrometry , 65-72, Copyright (2001), with permission from Elsevier Science.

The method for chloroacetanilide soil metabolites in water determines concentrations of ethanesulfonic acid (ESA) and oxanilic acid (OXA) metabolites of alachlor, acetochlor, and metolachlor in surface water and groundwater samples by direct aqueous injection LC/MS/MS. After injection, compounds are separated by reversed-phase HPLC and introduced into the mass spectrometer with a TurboIonSpray atmospheric pressure ionization (API) interface. Using direct aqueous injection without prior SPE and/or concentration minimizes losses and greatly simplifies the analytical procedure. Standard addition experiments can be used to check for matrix effects. With multiple-reaction monitoring in the negative electrospray ionization mode, LC/MS/MS provides superior specificity and sensitivity compared with conventional liquid chromatography/mass spectrometry (LC/MS) or liquid chromatography/ultraviolet detection (LC/UV), and the need for a confirmatory method is eliminated. In summary,... 

See footnote cto Table3 LC/PB/MS = hquid chromatography/particle beam mass spectrometry LC/APcl/ESl-MS/MS = liquid chromtography/atmospheric pressure chemical ionization/electrospray ionization tandem mass spectrometry LC/FTIR = Fourier transform infrared LC/TSP-MS/MS = liquid chromatography/thermospray tandem mass spectrometry LC/TSP-MS = liquid chromatography/thermospray mass spectrometry. 

The introduction and eventual commercialization of matrix-assisted laser desorption/ionization (MALDI) and electrospray (ESI) allowed biomarker status to be extended to proteins in 1996.15"17 With a few exceptions, ESI has been used in conjunction with extractions and high-pressure liquid chromatography (UPLC) interfaced with mass spectrometry. MALDI, on the other hand, has been widely adapted for rapid analysis of intact organisms, supported by bioinformatics.1819... 

For confirmatory assay, liquid chromatography-tandem mass spectrometry (LC-MS/MS) is becoming more frequently used in the analysis of OTC owing to its high sensitivity and ability. Electrospray ionization (ESI) [55-57] and atmospheric pressure chemical ionization (APCI) [41] methods combined with tandem mass spectrometry are favored because of their higher sensitivity and better reproducibility. Hamscher et al. [58] developed a method for the determination of persistent TC residues in soil fertilized with manure by HPLC tandem mass spectrometry, MS-MS, and confirmation by MS-MS-MS. Zhu et al. [59] developed an LC-tandem mass spectrometry for the analysis of common tetracyclines in water. The detection limit for oxytetracycline was 0.21 pg/L. Lykkeberg et al. [60] used LC-MS/MS for determination of oxytetracycline and its impurities EOTC, TC, ETC, ADOTC, oc-AOTC, and /i-AOTC. 

J. M. Wiseman, D. R. Ifa, Q. Song and R. G. Cooks, Tissue imaging at atmospheric pressure using Desorption Electrospray Ionization (DESI) mass spectrometry, Angew. Chem. Int. Edn, 45, 7188 7192 (2006). 

For the last several years, mass spectrometry with atmospheric pressure chemical ionization (APCI) and electrospray ionization (ESI) have determined the trends in the analysis of dyes. Since 1987, various variants of ESI have been used in which droplet formation was assisted by compressed air,[1,2] temperature (e.g. Turbo Ion Spray ) or ultrasound, and they were able to handle flow rates up to 1 2 ml min This made a combination of analytical RPLC and ESI easily and widely used. The reason why it often was (and is) used instead of a traditional UV-Vis detector is the better sensitivity and selectivity of MS in comparison with spectrophotometric detection. Apart from these advantages, MS offers easily interpretable structural information. However, various... 

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... 

In addition to the dissolved elements and compounds in the oceanic water column, a wide variety of water column chemicals are found in marine organisms and organic detritus. For example, a milliliter of surface seawater can contain on the order of 10 million viruses, 1 million bacteria, 100,000 phytoplankton, and 10,000 zooplankton [9]. With the advent of soft ionization processes for mass spectrometry systems, scientists have been able to study these marine organisms at molecular level. The use of electrospray ionization (ESI see Section 2.1.15), atmospheric pressure chemical ionization... 

K.L. Vikse, M.P. Woods, J.S. Mclndoe, Pressurized sample infusion for the continuous analysis of air- and moisture-sensitive reactions using electrospray ionization mass spectrometry, Organometallics 29 (2010) 6615-6618. 

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