Electrospray ionization applications

Wetterhall, M., Nilsson, S., Markides, K. E., and Bergquist, J. (2002). A conductive polymeric material used for nanospray needle and low-flow sheathless electrospray ionization applications. Anal. Chem. 74, 239-245. 

Wetterhall, M. Nillson, S. Markides, K.E. Bergquist, J. A Conductive Polymeric Material Used for Nanospray Needle and Low-Flow Sheathless Electrospray Ionization Applications, Anal. Chem. 74,239-245 (2002). 

Reza Anari, M., Bakhtiar, R., Zhu, B., Huskey, S., Franklin, R.B. and Evans, D.C., Derivatization of ethinylestradiol with dansyl chloride to enhance electrospray ionization application in trace analysis of ethinylestradiol in rhesus monkey plasma. Anal. Chem., 74, 4136 144 (2002). 

Journal of the American Society for Mass Spectrometry, Special Issue on Electrospray Ionization Applications to Peptide Protein Chemistry, Volume 4. 

Cole, R.B., Electrospray Ionization Mass Spectrometry Fundamentals, Instrumentation and Applications, Wiley, Chichester, U.K., 1997. 

Smith, R.M., Gas and Liquid Chromatography in Analytical Chemistry, Wiley, Chichester, U.K., 1988. Smith, R.M. and Busch, K.L., Understanding Mass Spectra A Basic Approach, Wiley, Chichester, U.K., 1998. Snyder, A.R, Biochemical and Biotechnological Applications of Electrospray Ionization Mass Spectrometry, Oxford University Press, Oxford, 1998. 

Electrospray ionization mass spectrometry (ESI-MS) is an analytical method for mass determination of ionized molecules. It is a commonly used method for soft ionization of peptides and proteins in quadmpole, ion-trap, or time-of-flight mass spectrometers. The ionization is performed by application of a high voltage to a stream of liquid emitted from a capillaty. The highly charged droplets are shrunk and the resulting peptide or protein ions are sampled and separated by the mass spectrometer. 

Two relatively new techniques, matrix assisted laser desorption ionization-lime of flight mass spectrometry (MALDI-TOF) and electrospray ionization (FS1), offer new possibilities for analysis of polymers with molecular weights in the tens of thousands. PS molecular weights as high as 1.5 million have been determined by MALDI-TOF. Recent reviews on the application of these techniques to synthetic polymers include those by Ilantoif54 and Nielen.555 The methods have been much used to provide evidence for initiation and termination mechanisms in various forms of living and controlled radical polymerization.550 Some examples of the application of MALDI-TOF and ESI in end group determination are provided in Table 3.12. The table is not intended to be a comprehensive survey. 

Matrix-assisted laser desorption ionization (MALDI) is not yet a technique that has been used extensively for LC-MS applications. It is included here because it often provides analytical information complementary to that obtained from LC-MS with electrospray ionization, as illustrated later in Chapter 5. 

Figure 4.20 Product-ion MS-MS spectrum from the doubly charged molecular ion of the peptide glu-fibrinogen B generated during electrospray ionization. From applications literature published by Thermofinnigan, Hemel Hempstead, UK, and reproduced with permission.

The effect of the buffer on the efficiency of electrospray ionization was mentioned earlier in Section 4.7.1. This is a good example of the dramatic effect that this may have - good chromatographic separation and ionization efficiency with formic, acetic and propionic acids, and good separation, although with complete suppression of ionization, with trifluoroacetic acid (TFA), the additive used for the protein application described previously. Post-column addition of propionic acid to the mobile phase containing TFA has been shown to reduce, or even... 

Cone-voltage fragmentation Fragmentation of ions, commonly produced by APCl or electrospray ionization, effected by the application of a voltage within the source of the mass spectrometer. 

Favretto, D. and Flamini, R., Application of electrospray ionization mass spectrometry to the study of grape anthocyanins. Am. J. Enol. Vitic., 51, 55, 2000. 

Strack, D. et al., Cyanidin 3-oxalylglncoside in orchids, J. BioscL, 41, 707, 1986. Choung, M.-G. et al.. Isolation and determination of anthocyanins in seed coats of black soybean (Glycine max (L.) Merr.), J. Agric. Food Chem., 49, 5848, 2001. Covey, T., Analytical characteristics of the electrospray ionization process, in Biochemical and Biotechnological Applications of Electrospray Ionization Mass Spectrometry, ACS Symposium Series, Snyder, A.P. and Anaheim, C. A., Eds., Washington, D.C., 1995, chap. 2. 

Snyder, A.P., Electrospray a popnlar ionization technique for mass spectrometry, in Biochemical and Biotechnological Applications of Electrospray Ionization Mass Spectrometry, ACS Symposium Series, Snyder, A.P. and Anaheim, C.A., Eds., Washington, D.C., 1995, chap. 1. 

As with GC/MS, LC/MS offers the possibility of unequivocal confirmation of analyte identity and accurate quantiation. Similarly, both quadrupole and ion-trap instruments are commercially available. However, the responses of different analytes are extremely dependent on the type of interface used to remove the mobile phase and to introduce the target analytes into the mass spectrometer. For pesticide residue analyses, the most popular interfaces are electrospray ionization (ESI) and atmospheric pressure chemical ionization (APCI). Both negative and positive ionization can be used as applicable to produce characteristically abundant ions. 

Electrospray ionization (ESI) and APCI are the two popular API techniques that will be discussed here. The applications to the analysis of pesticides that will be discussed include imidazolinone herbicides, phenoxy acid herbicides, and A-methyl carbamate insecticides. Matrix effects with respect to quantitation also will be discussed. Eor the... 

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. 

Wang, G. Cole, R. B. In Electrospray Ionization Mass Spectrometry Fundamentals Instrumentation and Applications. Cole, R. B. (Ed.). New York Wiley, 1997, pp. 137-174. 

The most important techniques belonging to this class are electrospray ionization (ESI), atmospheric pressure chemical ionization (APCI) and, more recently, atmospheric pressure photoionization (APPI). At present the latter does not have applications in cultural heritage, so it will be not described here. 

Z. Takats, J. M. Wiseman and R. G. Cooks, Ambient mass spectrometry using desorption electrospray ionization (DESI) instmmentation, mechanisms and applications in forensics, chemistry, and biology, J. Mass Spectrom., 40, 1261 1275 (2005). 

Cuyckens F, Shahat AA, Van den Heuvel H, Abdel-Shafeek KA, El-Messiry MM, Seif-El Nasr MM, Pieters L, Vlietinck AJ and Claeys M. 2003. The application of liquid chromatography-electrospray ionization mass spectrometry and collision-induced dissociation in the structural characterization of acylated flavonol O-glycosides from the seeds of Carrichtera annua. Eur J Mass Spectrom 9(4) 409-420. 

Raices R.S.L. et al., 2003. Determination of stavudine in human serum by online solid-phase extraction coupled to high-performance liquid chromatography with electrospray ionization tandem mass spectrometry Application to a bioequivalence study. Rapid Commun Mass Spectrom 17 1611. 

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