Mass spectrometry analytical applications

Fourier Transform Ion Cyclotron Resonance Mass Spectrometry Analytical Applications 1st ed. Asamoto, B., editor John Wiley Sons New York, 1991. 

Electron ionization (El) is surely the ionization method most widely employed (Mark and Dunn, 1985). This method was proposed and used from the early days of mass spectrometry (MS) applications in the chemical world and is still of wide interest. This interest is due to the presence of libraries of El mass spectra, which allows easy identification of unknown previously studied analytes. The El method suffers from two limitations It is based on the gas-phase interactions between the neutral molecules of the analyte and an electron beam of mean energy 70 eV. This interaction leads to the deposition of internal energy in the molecules of the analyte, which is reflected in the production of odd-electron molecular ([M]+ ) and fragment ions. These ions are highly diagnostic from a structural point of view. 

Gardner WP, Shaffer RE, Girard JE, Callahan JH, Application of quantitative chemometric analysis techniques to direct sampling mass spectrometry, Analytical Chemistry, 2001, 73, 596-605. 

See also Bloassays Overview. Derivatizatlon of Analytes. Extraction Solvent Extraction Principles. Fluorescence Food Applications. Food and Nutritional Analysis Contaminants. Gas Chromatography Detectors Mass Spectrometry. Immunoassays Production of Antibodies. Immunoassays, Applications Food. Immunoassays, Techniques Enzyme Immunoassays. Liquid Chromatography Instrumentation Liquid Chromatography-Mass Spectrometry Food Applications. Sampling Theory. 

See also. Analytical Reagents Specification. Derivat-ization of Analytes. Fluorescence Derivatization Fluorescence Labeling Quantitative Anaiysis. Lipids Fatty Acids. Liquid Chromatography Liquid Chromatography-Mass Spectrometry Pharmaceuticai Applications. Mass Spectrometry Forensic Appiications. Spectrophotometry Derivative Techniques. 

See also Clinical Analysis Sample Handling. Derivatization of Analytes. Forensic Sciences Systematic Drug Identification Thin-Layer Chromatography. Fourier Transform Techniques. Gas Chromatography Mass Spectrometry Forensic Applications. Immunoassays, Applications Clinical Forensic. Liquid Chromatography Normal Phase Reversed Phase. Spectrophotometry Pharmaceutical Applications. 

In Chapter 4, titled Principles of Mass Spectrometry Imaging Applicable to Thin-Layer Chromatography, the authors first introduce a budding analytical approach known as imaging mass spectrometry (IMS) strategy and then present some successful examples of its practical applications. Then, they introduce in detail three mass spectrometric techniques as those routinely used within the framework of IMS. These are secondary mass spectrometry (SIMS), matrix-assisted laser desorption/ ionization (MALDI-IMS), and desorption electrospray ionization (DESI). Finally, the authors discuss the advances and bottlenecks of these techniques when applied to TLC. 

Thomas JJ, Shen Z, Blackledge R, Siuzdak G (2001b) Desorption-ionization on silicon mass spectrometry an application in forensics. Anal Chim Acta 442 183-190 Trauger SA, Go EP, Shen Z, Apon JV, Compton BJ, Bouvier ESP, Finn MG, Siuzdak G (2004) High sensitivity and analyte capture with desorption/ionization mass spectrometry on silylated porous silicon. Anal Chem 76 4484-4489... 

Shockcor JP, Unger SE, WUson ID, Foxall PJD, Nicholson JK and Lindon JC (1996) Combined HPLC, NMR spectroscopy, and ion-trap mass spectrometry with application to the detection and characterization of xenobiotic and endogenous metabolites in human urine. Analytical Chemistry 68 4431-4435. 

Ventura, R., Damasceno, L., Farre, M., et al. (2000) Analytical methodology for the detection of beta(2)-agonists in urine by gas chromatography-mass spectrometry for application in doping control. Analytica Chimica Acta, 418,79-92. 

Budde, W.L., Analytical Mass Spectrometry Strategies for Environmental and Related Applications, American Chemical Society, Washington, D.C., 2001. 

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. 

This unique reference makes some of the esoteric aspects of this important area of analysis more readily comprehensible to those who deal with analytical instruments but who have not been trained in mass spectrometry. It also serves as a refresher for practicing mass spectroscopists by clarifying principles to afford a better appreciation and application of this technology. 

Laser based mass spectrometric methods, such as laser ionization (LIMS) and laser ablation in combination with inductively coupled plasma mass spectrometry (LA-ICP-MS) are powerful analytical techniques for survey analysis of solid substances. To realize the analytical performances methods for the direct trace analysis of synthetic and natural crystals modification of a traditional analytical technique was necessary and suitable standard reference materials (SRM) were required. Recent developments allowed extending the range of analytical applications of LIMS and LA-ICP-MS will be presented and discussed. For example ... 

The abundance of a trace element is often too small to be accurately quantihed using conventional analytical methods such as ion chromatography or mass spectrometry. It is possible, however, to precisely determine very low concentrations of a constituent by measuring its radioactive decay properties. In order to understand how U-Th series radionuclides can provide such low-level tracer information, a brief review of the basic principles of radioactive decay and the application of these radionuclides as geochronological tools is useful. " The U-Th decay series together consist of 36 radionuclides that are isotopes (same atomic number, Z, different atomic mass, M) of 10 distinct elements (Figure 1). Some of these are very short-lived (tj j 1 -nd are thus not directly useful as marine tracers. It is the other radioisotopes with half-lives greater than 1 day that are most useful and are the focus of this chapter. 

In gas chromatography/mass spectrometry (GC/MS), the effluent from a gas chromatograph is passed into a mass spectrometer and a mass spectrum is taken every few milliseconds. Thus gas chromatography is used to separate a mixture, and mass spectrometry used to analyze it. GC/MS is a very powerful analytical technique. One of its more visible applications involves the testing of athletes for steroids, stimulants, and other performance-enhancing drugs. These drugs are converted in the body to derivatives called metabolites, which are then excreted in the... 

In order to reduce or eliminate off-line sample preparation, multidimensional chromatographic techniques have been employed in these difficult analyses. LC-GC has been employed in numerous applications that involve the analysis of poisonous compounds or metabolites from biological matrices such as fats and tissues, while GC-GC has been employed for complex samples, such as arson propellants and for samples in which special selectivity, such as chiral recognition, is required. Other techniques include on-line sample preparation methods, such as supercritical fluid extraction (SFE)-GC and LC-GC-GC. In many of these applications, the chromatographic method is coupled to mass spectrometry or another spectrometiic detector for final confirmation of the analyte identity, as required by many courts of law. 

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. 

Commercial Instruments Because of the proliferation of applications of mass spectrometry in organic and analytical chemistry, there are instruments marketed by numerous companies today. Some of the popular ones are the low resolution, single focusing model 21-490 and the high resolution, double focusing models, 21-492 and 21-110 of Du Pont de Nemours Co, and the double focusing model MS-9 of Associated Electrical Industries... 

Analytical applications Mass spectrometry has been applied to a variety of analytical problems related to expls, some of which have already been mentioned. Identification of the principal constituents of expls has been attempted from electron impact cracking patterns (Refs 34, 50 58), as well as chemical ionization spectra (Refs 69,70 71). Such methods necessarily include vapor species analysis and are directed to detection of buried mines (Refs 50, 58, 61,... 

Figure 4.3 Schematic of a continuous-flow FAB LC-MS interface. From applications literature published by Kratos Analytical Ltd, Manchester, UK, and reproduced by permission of Mass Spectrometry International Ltd.

In the vast majority of GC-MS applications, the chromatographic conditions employed have little or no effect on the operation of the mass spectrometer. This means that the spectrometer may be tuned for optimum performance and a number of samples containing different analytes can be analysed without operator intervention. This is not the case with LC-MS where the chromatographic conditions will invariably have a significant, compound-dependent, effect on the mass spectrometry conditions required to obtain useful analytical data. 

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. 

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