Spray ionization

Peaks are analyzed separately by their retention times, absorption, and fluorescence properties. RCCs show absorbance maxima near A.500 and 316 nm. For FCCs, UV-Vis specna show two prominent bands near 361 and 320 mn and a luminescence maximum at 436 mn and NCCs show UV-Vis spectra with absorbance maxima near 320 and 210 nm. Nevertheless, as none of these approaches is suitable for elucidating structures, it is necessary to apply additional MS and NMR analyses to fully characterize snuctural features. Electron spray ionization (ESI) and high-resolution EAB mass spectroscopy have been applied to elucidate the molecular formulae of colorless compounds. ... 

A detailed description of sources used in atmospheric pressure ionization by electrospray or chemical ionization has been compiled.2 Atmospheric pressure has been used in a wide array of applications with electron impact, chemical ionization, pressure spray ionization (ionization when the electrode is below the threshold for corona discharge), electrospray ionization, and sonic spray ionization.3 Interferences potentially include overlap of ions of about the same mass-charge ratio, mobile-phase components, formation of adducts such as alkali metal ions, and suppression of ionization by substances more easily ionized than the analyte.4 A number of applications of mass spectroscopy are given in subsequent chapters. However, this section will serve as a brief synopsis, focusing on key techniques. 

Soft ionization methods can be classified into different groups (a) those occurring in the gas phase (b) spray ionization techniques (c) desorption ionization techniques. 

The ionization techniques described above occur in ion sources that are maintained under high vacuum. In contrast, spray ionization techniques operate at atmospheric pressure a solution spraying from a capillary is ionized at atmospheric pressure and the ions produced are driven into the high vacuum of the mass analyzer where they are separated. The use of spray and desorption ionizations does not require volatilization of the sample before ionization. This means that all these techniques can ionize nonvolatile, polar and large to very large compounds. 

Castellanos-Santiago E and Yahia EM. 2008. Identification and quantification of betalaines from the fruits of 10 Mexican prickly pear cultivars by high-performance liquid chromatography and electron spray ionization mass spectrometry. J Agric Food Chem 56 5758-5764. 

Fig. 19.14. Accumulation of phosphate salts in the atmospheric pressure ionization chamber. Note the large accumulation of salts on the striker plate. Additional accumulation of salts can be seen on the back walls of the chamber. The general dustiness in the chamber is salt accumulation. This source is a z-spray ionization source chamber of a Micromass Quattro Ultima mass spectrometer system.

Mccomb, M. E., and Perreault, H. (2000). Design of a sheathless capillary electrophoresis-mass spectrometry probe for operation with a Z-Spray ionization source. Electrophoresis 21, 1354-1362. 

The use of diisoprop anolamine in the synthesis of the hyperbranched poly-esteramide resins has led to defined molecules according to the predicted structures (Fig. 7) as confirmed by MALDI-TOF (Matrix Assisted Laser Desorption Ionization - Time Of Flight) and ESI (Electro Spray Ionization) mass spectra... 

A home-built spray ion source, operable in both the sonic-spray ionization (SSI) and electrospray ionization (ESI) modes, was used instead of the standard ESI source of the Einnigan LCQ instrument. (Erom Takats et al., 2003b)... 

Takats, Z. Nanita, S. C. Cooks, R. G. Schlosser, G. Vekey, K. Amino Acid Clusters Formed by Sonic Spray Ionization. Anal Chem. 2003a, 75, 1514-1523. 

The real breakthrough in LC/MS development was achieved with the broad introduction in the 1990s of atmospheric pressure ionization (API) techniques, such as electrospray ionization (ESI) and atmospheric pressure chemical ionization (APCI), which enable the analysis of a wide variety of molecular species. The spectrum of available API techniques has been amended meanwhile by the introduction of sonic spray ionization (SSI) and atmospheric pressure photoionization (APPI). 

Hamscher G., S. Sczesny, H. Hdper, and H. Nau (2002). Determination of persistent tetracycline residues in soil fertilized with liquid manure by high-performance liquid chromatography with electron spray ionization tandem mass spectrometry. Analytical Cheminstry 74 1509-1518. 

Vivas, N. et al.. Differentiation of proanthocyanidin tannins from seeds, skins and stems of grapes Vitis vinifera) and heartwood of Quebracho (Schinopsis balansae) by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry and thioacidolysis/liquid chromatography/electro-spray ionization mass spectrometry. Anal Chim. Acta, 513, 247, 2004. 

Gu, L. et al.. Liquid chromatography/electron spray ionization mass spectrometric studies of proanthocyanidins in foods, J. Mass Spectrom., 38, 1272, 2003. 

ESI tandem MS stands for electro spray ionization mass spectrometry performed in multistage. This technique is conducted based on the production of multiply charged ions from proteins and peptides. In this technique, ionization procedure is carried out within the instrument. Three types of mass analyzers are used individually or in combination. 

ERH equilibrium relative humidity ESI electro spray ionization FAB/MS fast atom bombardment mass spectrometry... 

Wiseman, J. M., Takats, Z., Gologan, B., Davisson, V. J., and Cooks, R. G. (2005). Direct characterization of enzyme-substrate complexes by using electrosonic spray ionization mass spectrometry. Angew Chem. Int. Ed. Engl. 44 913-916. 

Mass spectrometry (MS) is a very sensitive method of determining the mass of native proteins, as well as their purity. The two most common techniques are ESI-MS (electron spray ionization-MS) and MALDI-TOF-MS (matrix-assisted laser... 

The stoichiometry of the extracted M(III) complexes differs from that of the above-mentioned BTP ligands in that M L2 complexes (instead of M L3 complexes) have been identified by various techniques (e.g., X-ray crystallography, nuclear magnetic resonance, electro-spray ionization mass-spectrometry, and slope analysis in liquid-liquid extraction). 

The mass spectrometry portion of the analysis was carried out by coupling a Bruker Esquire ion-trap mass spectrometer to the LC-NMR system with a 20 1 splitter. The major portion of the flow was directed to the NMR system while the minor fraction went to the mass spectrometer. The system was plumbed such that the sample reached the mass spectrometer and the UV detector at the same time. In this configuration, it is possible to use the mass spectrometer as an intelligent detector, thus allowing stop-flow experiments to be initiated on the basis of observed molecular ions or daughter ion fragments. Data were acquired with electro-spray ionization (ESI) in the positive-ion mode. 

Column Hypersil GOLD Ci8 column (2.1 mm x 150 mm) Detector LC-MS/MS operated in turbo ion spray ionization MRM monitoring ... 

Kanazawa et al. [124] determined omeprazole and its metabolites in human plasma by liquid chromatography-three-dimensional quadrupole mass spectrometry with a sonic spray ionization interface. The analytical column was YMC-Pack Pro Cig (5 cm x 2 mm) using acetonitrile-50 mM ammonium acetate (pH 7.25) (1 4) at a flow-rate of 0.2 ml/min. The drift voltage was 30 V. The sampling aperture was heated at 110 °C and shield temperature was 230 °C. In the mass spectrum, the molecular ions of omeprazole, hydroxyomeprazole, and omeprazole sulfone were clearly observed as base peaks. The method is sufficiently sensitive and accurate for pharmacokinetic studies of omeprazole. 

Gardner, J. S., Harrison, R. G., Lamb, J. D., Dearden, D. V., Sonic spray ionization mass spectrometry a powerful tool used to characterize fragile metal-assembled cages. New]. Chem. 2006, 30, 1276-1281. 

Fig. 3. Electro spray ionization mass spectrometry of the product generated by recombinant GalNAcT. Spectra were acquired in the negative mode. The molecular weight of globotetraose is 706.8. The ion peak at m/z 705.83 is attributed to the molecular ion M-H] of globotetraose.

Trimethylguanine Dimethyl sulfoxide Electro spray ionization mass... 

From the analyses of NMR and electron-spray ionization mass (ESI-MS) spectroscopy, the polymers obtained from the polymerization of cyclic disulfides were found to be a cyclic structure [202], The cyclic structure consisting of poly(DT) is assumed to be formed by a backbiting reaction of propagating species [203]. Thermal and mechanical properties of the polymers, and decomposition behaviors of the polymers demonstrate that the polymers obtained from thermal polymerization of cyclic disulfides include a polycatenane structure. From polymerization of cyclic disulfides in the presence of cyclic polyethylene oxide), a polycatenane consisting of two different cyclic polymers was obtained [199]. Thus, poly(DT) contains spatial entanglements of cyclic polymers with each other (a polycatenane structure was presumed) (Fig. 61). 

LLE liquid-liquid extraction, SPE solid phase extraction, LPME liquid-phase microextraction, ESI electrospray ionization, APCI atmospheric pressure chemical ionization, SSI sonic spray ionization, Q quadrupole, QqQ triple quadrupole, TOF time-of-flight, IT ion trap, IS internal standard, CV coefficient of variation, MRE mean relative error, LOD limit of detection, LLOQ lower limit of quantification... 

The native molecular weight (M) of 83.0 kdal is determined independently with electron spray ionization mass spectrometry. If the protein is spherical and unhydrated, its radius (r0) can be estimated by... 

The thus prepared ligands la-le-H4 are introduced into coordination studies with titanium(IV) ions in the presence of base (M2C03 M = Li, Na, K) with methanol as solvent. Negative ESI-MS (electron spray ionization mass spectrometry) of the obtained orange-red solids in methanol reveals that coordination compounds of general formula M2[l2(OCH3)2Ti2] are formed (Scheme 1.3.2) [20, 21]. 

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