Electrospray ionization carbohydrates

Black, G.E. and Fox, A., Liquid chromatography with electrospray ionization tandem mass spectrometry profiling carbohydrates in whole bacterial cell hydrolysates, in Biochemical and Biotechnological Applications of Electrospray Ionization Mass Spectrometry, ACS Symposium Series, Snyder, A.P. and Anaheim, C.A., Fids., Washington, D.C., 1995, chap. 4. 

The growing interest for the identification and characterization of polar and large compounds caused the development and the introduction of new ionization techniques, such as electrospray ionization (ESI)[4], and matrix assisted laser desorption ionization (MALDI),[5] and their more recent improvements, thus establishing new MS based approaches for studying large molecules, polymers and biopolymers, such as proteins, carbohydrates, nucleic acids. 

FEURLE, J., JOMAA, H., WILHELM, M GUTSCHE, W.B., HERDRICH, M., Analysis of phosphorylated carbohydrates by high-performance liquid chromatography-electrospray ionization tandem mass spectrometry utilising p-cyclodextrin bonded stationary phase, J. Chromatogr., 1998,803,111-119. 

Carbohydrates show a considerable affinity toward alkali cations, which are frequently used for their mass spectral analyses. Lithium cation exhibits specific affinity toward glucose, as has been detected by electrospray ionization mass spectrometry. The experimental results were found to be consistent with the ab initio theoretical calculations and confirm the following order of stability of the M+-glucose complexes [gl-Li] > [gl-Na]+ > [gl-K]+4 . 

Electrospray mass spectrometry has developed into a well-established method of wide scope and potential over the past 15 years. The softness of electrospray ionization has made this technique an indispensable tool for biochemical and biomedical research. Electrospray ionization has revolutionized the analysis of labile biopolymers, with applications ranging from the analysis of DNA, RNA, oligonucleotides, proteins as well as glycoproteins to carbohydrates, lipids, gly-colipids, and lipopolysaccharides, often in combination with state-of-the-art separation techniques like liquid chromatography or capillary electrophoresis [1,2]. Beyond mere analytical applications, electrospray ionization mass spectrometry (ESMS) has proven to be a powerful tool for collision-induced dissociation (CID) and multiple-stage mass spectrometric (MSn) analysis, and - beyond the elucidation of primary structures - even for the study of noncovalent macromolecular complexes [3]. 

Y. Fukuyama, M. Ciancia, H. Nonami, A. S. Cerezo, R. Erra-Balsells, and M. C. Matulewicz, Matrix-assisted ultraviolet laser-desorption ionization and electrospray-ionization time-of-flight mass spectrometry of sulfated neocarrabiose oligosaccharides, Carbohydr. Res., 337 (2002) 1553-1562. 

The majority of reports have used electrospray ionization mass spectroscopy (ESI-MS) as an analytical detection method because of its sensitivity and the soft namre of its ionization procedure, which generally only leads to the detection of the molecular ions of the positive library members. Many separation techniques have been coupled to ESI-MS, including affinity chromatography (49), size exclusion chromatography (50, 51), gel filtration (52), affinity capillary electrophoresis (53-58), capillary isoelectric focusing (59), immunoaffinity ultrafiltration (60), and immunoaffinity extraction (61). ESI-MS has also been used alone (62) to screen a small carbohydrate library. Other examples reported alternative analytical techniques such as MALDI MS, either alone (63, 64) or in conjunction with size exclusion methods (65), or HPLC coupled with immunoaffinity deletion (66). 

In recent years there has been a growing interest in the use of electrospray ionization-mass spectrometry (ESI-MS) either as a stand-alone technique, or following an analytical separation step like CE, to study and measure a wide variety of compounds in complex samples such us foods (Simo et al. 2005). ESI provides an effective means for ionising from large (e.g., proteins, peptides, carbohydrates) to small (e.g., amino acids, amines) analytes directly from solution prior to their MS analysis without a previous derivatization step. Santos et al. (2004) proposed the use of CE-ESI-MS for the separation and quantification of nine biogenic amines in white and red wines. More recently, the possibilities of two different CE-MS set-ups, namely, capillary electrophoresis-electrospray-ion trap mass spectrometry (CE-IT-MS) and capillary electrophoresis-electrospray-time of flight mass spectrometry (CE-TOE-MS) to analyze directly biogenic amines in wine samples without any previous treatment has been studied (Simo et al. 2008). 

The presence of pentosyUiexosides, trisaccharides and tetrasaccharides has been reported in different wines using positive- and negative-ion electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry (Cooper and Marshall 2001). Nevertheless, at present there are still a number of minor carbohydrates in wines without a conclusive identification. 

After isolation and identification of the peptides containing these glycosylation sites, high pH anion exchange chromatography, matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry, and electrospray ionization mass spectrometry (ES-MS) were utilized to evaluate carbohydrate microheterogeneity. 

The characterization of water-soluble components in slurries is one use of SPME with mixed solid-liquid samples. In one application, dried homogenized solid samples (10 mg of sewage sludge or sediment) were slurried in 4 ml of H,0 saturated with NaCl and adjusted to pH 2 with HCl for extraction for 1-15 h, which was followed by desorption into 4 1 methanol/ethanol over 2 min. The extracted compounds were either injected into a liquid chromatograph or fed directly via an electrospray ionization interface to a mass spectrometer with 1 s miz scans from 50-700 or selected-ion monitoring. The major components extracted included phthalates, fatty acids, non-ionic surfactants, chlorinated phenols and carbohydrate derivatives [235]. 

Mass spectrometry is an important method in determining carbohydrate structures, and there are excellent reviews of the most recent mass spectrometric methods for complex carbohydrates [16,17]. Among many useful techniques, classical ionization of volatile molecules through electron impact (El) or chemical ionization (Cl) [18,19], electrospray ionization (ESI) [20], and field desorption techniques (ED) [21] are frequently employed in structural analysis. 

For detection of carbohydrates in principle, ultraviolet (UV), laser-induced fluorescence, refractive index, electrochemical, amperometric, and mass spec-trometric detection can be used. Mass spectrometry, with its various ionization methods, has traditionally been one of the key techniques for the structural determination of proteins and carbohydrates. Fast-atom bombardment (FAB) and electrospray ionization (ESI) are the two on-line ionization methods used for carbohydrate analysis. The ESI principle has truly revolutionized the modern mass spectrometry of biological molecules, due to its high sensitivity and ability to record large-molecule entities within a relatively smaU-mass scale. 

K. Yamashita, T. Ohkura, H. Ideo, K. Ohno and M. Kanai, Electrospray ionization-mass spectrometric analysis of serum transferrin isoforms in patients with carbohydrate-deficient glycoprotein syndrome, J. Biochem. (Tokyo), 114, 766-769 (1993). 

Mass Spectrometry. Soft ionization techniques of fast atom bombardment (FAB), electrospray ionization (ES), or matrix-assisted laser desorption ionization (MALDI) have advanced carbohydrate analysis (146, 147). 

Zamfir, A., Koiug, S., Althoff, J. and Peter-Katalinc, J. Capillary electrophoresis and off-line capillary electrophoresis-electrospray ionization quadrupole time-of-flight tandem mass spectrometry of carbohydrates. J Chromatogr A, 895, 291, 2000. 

Lee, D.S. Wu, C. HiU, H.H., Detection of carbohydrates by electrospray-ionization ion mobihty spectrometry foUowing microbore high-performance hquid-chromatography, J. Chromatog. A 1998, 822, 1-9. 

FIGURE 8.9 Selectivity induced by cation adduction. Ion mobility separation of methyl-p-D-galactopyranoside from its isomer methyl-a-D-galactopyranoside using different cation adducts. (From Dwivedi et al., Rapid resolution of carbohydrate isomers by electrospray ionization ambient pressure ion mobility spectrometry-time-of-flight mass spectrometry (ESI-APIMS-TOFMS), J. Am. Soc. Mass Spectrom. 2007, 18, 1163-1175. With permission.)... 

Figure 9.13 Positive ion spray mass spectrum of galactosyl ceramide (Galcer) (50 nmol ml" ) with (500 nmol ml" ) in methanol. The declustering potential was 80 V. Reproduced with permission from Koshy, K. M. and Boggs, J. M., Investigation of the calcium-mediated association between the carbohydrate head groups of galactosylceramide and galactosylceramide I sulphate by electrospray ionization mass spectrometry, J. Biol Chem., 271(7), 3496-9, 1996.

Zhang, Y, Ren, Y, Zhao, H., and Zhang, Y. 2007. Determination of acrylamide in Chinese traditional carbohydrate-rich foods using gas chromatography with microelectron capture detector and isotope dilution liquid chromatography combined with electrospray ionization tandem mass spectrometry. Anal. Chim. Acta. 584 322-332. 

Yu, Z., Chen, L.C., Suzuki, H., Ariyada, O., Erra-Balsells, R., Nonami, H., Hiraoka, K. (2009) Direct Profiling of Phytochemicals in Tulip Tissues and In Vivo Monitoring of the Change of Carbohydrate Content in Tulip Bulbs by Probe Electrospray Ionization Mass Spectrometry. J. Am. Soc. Mass Spectrom. 20 2304-2311. 

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