Electrospray ionization source

Different types of ion sources used in mass spectrometry are compared in Table 2.2. Several plasma ion sources applied in analytical atomic spectrometry were described by Broekaert.33 

Ion source Atomization Ionization Plasma temperature Electron density Ions measured Vacuum condition Mass analyzer utilized Application 

Inductively coupled in Ar plasma by Wa 6000-8000K M+ atmospheric quadrupole, ToF-MS, traces, ultratraces, 

Spark ion source in spark plasma by e impact plasma 50 000 ne 1 018-1019 crrr3 M+ high 1( 4 Pa double-focusing SFMS (Mattauch-Herzog) traces, high-purity materials, geology 

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Geromanos, S., Freckleton, G., and Tempst, P., Tuning of an electrospray ionization source for maximum peptide-ion transmission into a mass spectrometer, Anal. Chem., 72, 777, 2000. 

Different mass analysers can be combined with the electrospray ionization source to effect analysis. These include magnetic sector analysers, quadrupole filter (Q), quadrupole ion trap (QIT), time of flight (TOF), and more recently the Fourrier transform ion cyclotron resonance (FTICR) mass analysers. Tandem mass spectrometry can also be effected by combining one or more mass analysers in tandem, as in a triple quadrupole or a QTOF. The first analyzer is usually used as a mass filter to select parent ions that can be fragmented and analyzed by subsequent analysers. 

Juraschek, R. Dulcks,T. Karas, M. Nanoelectrospray—More than just a minimized flow electrospray ionization source. /. Am. Soc. Mass Spectrom. 1999,10,300-308. 

Electroslag remelting, 23 255 Electroslurry process, 23 576 Electrospinning, 11 186 Electrospray ionization, liquid chromatography, 4 625 Electrospray ionization source, 15 654-658 Electrostatic atomization, in spray coating, 7 72-73... 

Usually ion trap mass spectrometers are combined with an electrospray ionization source (Fig. 1). Ions are transferred into a region that is... 

High-performance liquid chromatography (HPLC) techniques are widely used for separation of phenolic compounds. Both reverse- and normal-phase HPLC methods have been used to separate and quantify PAs but have enjoyed only limited success. In reverse-phase HPLC, PAs smaller than trimers are well separated, while higher oligomers and polymers are co-eluted as a broad unresolved peak [8,13,37]. For our reverse-phase analyses, HPLC separation was achieved using a reverse phase. Cl8, 5 (Jtm 4.6 X 250 mm column (J. T. Baker, http //www.mallbaker.com/). Samples were eluted with a water/acetonitrile gradient, 95 5 to 30 70 in 65 min, at a flow rate of 0.8 mL/min. The water was adjusted with acetic acid to a final concentration of 0.1%. All mass spectra were acquired using a Bruker Esquire LC-MS equipped with an electrospray ionization source in the positive mode. 

Figure 4 The Electrospray Ionization Source Generates Ions via Charged Droplet Evaporation Followed by Electrostatic Direction of the Ions into a Mass Analyzer...

The mass analyzer should be calibrated on a regular basis by infusing a calibration solution. In general, an electrospray ionization source (ESI) is used. The solution should produce ions (with known exact masses) that cover the entire instrument mass range or at least the mass range that will be used for subsequent analyses. 

Y. Yang, J. Kameoka, T. Wachs, J.D. Herion and H.G. Craighead, Quantitative mass spectrometric determination of methylphenidate concentration in urine using an electrospray ionization source integrated with a polymer microchip, Anal. Chem., 76 (2004) 2568-2574. 

A sensitive, simple, and specific liquid chromatographic method coupled with electrospray ionization-mass spectrometry for the determination of donepezil in plasma was developed, and its pharmacokinetics in healthy, male, Chinese was studied [34]. Using loratadine as the IS, after extraction of the alkalized plasma by isopropyl alcohol-n-hexane (3 97, v/v), solutes are separated on a Cig column with a mobile phase of methanol-acetate buffer (pH 4.0) (80 20, v/v). Detection is performed with a TOF mass spectrometer equipped with an electrospray ionization source operated in the positive-ionization mode. Quantitation of donepezil is accomplished by computing the peak area ratio (donepezil [M + H](+) m/z 380-loratadine [M + H](+) mlz 383) and comparing them with the calibration curve (r = 0.9998). The linear calibration curve is obtained in the concentration range 0.1-15 ng/ml. The limit of quantitation is 0.1 ng/ml. The mean recovery of donepezil from human plasma is 99.4 6.3% (range 93.4-102.6%). The inter- and intra-day RSD is less than 15%. After an oral administration of 5 mg donepezil to 20 healthy Chinese volunteers, the main pharmacokinetic parameters of donepezil are as follow T(max), 3.10 0.55 h tV2j 65.7 12.8 h C(max), 10.1 2.02 ng/ml MRT,... 

Kameoka, J., Orth, R., Ilic, B., Czaplewski, D., Wachs, T., Craighead, H.G., An electrospray ionization source for integration with microfluidics. Anal. Chem. 

The synthesis of phosphopeptides is typically confirmed mass spectrometri-cally using either a MALDI (matrix-assisted laser desorption/ionizafion) or an ESI (electrospray ionization) source, and the peptide purity is determined by reversed-phase chromatography coupled to an UV detector (Figs. 1 and 2B). Whenever possible, phosphopeptide analyses should be complimented by mass spectra recorded in negative ion mode. For most biochemical applications it is necessary to purify the peptides by HPLC techniques (Fig. 2A). 

A Perkin Elmer Series 200 pump and a Perkin Elmer ISS200 autosmapler (Perkin Elmer, Norwalk, CT, USA) have been used as the HLPC system, connected to an API 365 triple quadrupole mass spectrometer (Sciex, Thornhill, ON, Canada). The mass spectrometer was equipped with an Electrospray ionization source. 

For mass spectrometric detection, a TSQ 7000 triple quadrupole mass spectrometer (Finnigan MAT, USA) equipped with an Electrospray ionization source was. 

LC ESI (8) mass spectra were recorded on a Finnigan TSQ700 instrument (San Jose, CA) in positive ion mode. A sample aliquot was injected into a fused silica microcapillary column with an inside diameter of 100 pm. The microcapillary was filled at the end with 10 cm of a C-18 reversed phase resin. PMP labeled oligosaccharides were eluted at ca. 1 pL/min directly into the electrospray ionization source with a 10 min gradient of acetic acid in H2O (0.5 %, v/v) to 80 % acetonitrile. Determination of experimental molecular weights was done with the deconvolution software provided by the manufacturer. 

With electrospray ionization, a fine mist of highly charged particles is produced when a liquid flows from a capillary tube into a strong electrical field (3 to 6kV).In practice, electrospray ionization sources are often directly coupled with reversed phase HPLC or capillary columns. The ability to couple a liquid chromatograph with an electrospray ionization source and a mass spectrometer allows the online removal of salts and contaminants and the analysis of complex mixtures. Although different from MALDI, electrospray provides similar sensitivity and application to the analysis of large proteins. 

Figure 4 Schematic of a generic electrospray ionization source.

Although APCI can accommodate higher flow rates (up to approximately 2 mL/min), the source is usually operated at higher temperatures than an electrospray ionization source, which can lead to thermal degradation of the sample. This is especially problematic with the detection of fragile glucuronides, N-oxides, and sulfates. Either ion source can accommodate a wide range of EIPLC mobile-phase... 

Fig. 5.3. A photograph of the spray generated in an electrospray ionization source (top) and a schematic view of the processes involved (bottom). From the Taylor cone, a jet is emitted and expands to a plume of micrometer-sized charged droplets from which finally desolvated ions are produced.

Geronmanos, S. Freckleton, G. Tempst, P. Tuning of an Electrospray Ionization Source for Maximum Peptide-Ion Transmission into a Mass Spectrometer," Anal. Chem. 72,777-790 (2000). 

Triversa Nanomate or any other nanoflow electrospray ionization source... 

Gomez-Ariza, J.L., Arias-Borrego, A., Garcia-Barrera, T., and Beltran, R., Comparative study of electrospray ionization sources coupled to quadrupole time-of-flight mass spectrometer for olive oil authentication, Talanta, 70, 859-869, 2006. 

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