Mass spectrometric techniques identification

Mass Spectrometric Technique Identification Points per Ion Monitored... 

Gibson, B. W. Phillips, N. J. John, C. M. Melaugh, W. Lipooligosaccharides in pathogenic Haemophilus and Neisseria species—Mass spectrometric techniques for identification and characterization. ACS Sympo. Ser. 1994,541,185-202. 

The development of mass spectrometric techniques for nuclide identification using a tandem Van de Graaff accelerator at the University of Rochester Nuclear Structure Laboratory by H. Gove, K. Purser, A. Litherland, and numerous associates has provided an excellent means for the precise measurement of 36C1 concentrations in natural water [43]. Thus far, about 40 groundwater related samples which have been collected and purified chemically by H. Bentley have been analyzed for 36C1 by D. Elmore, H. Bentley, and others using the University of Rochester machine. Some of these samples are listed in Table 2. 

He, X.-G., On-line identification of phytochemical constituents in botanical extracts by combined high-performance liquid chromatographic-diode array detection-mass spectrometric techniques, J. Chromatogr. A, 880, 203, 2000. 

With respect to sample preparation, it is necessary to develop effective and fast procedures involving only a few steps in order to avoid contamination, reduce analysis time and to improve the quality of analytical work. Microsampling and the use of smaller sample sizes is required and also the further development of analytical techniques. In particular, there is a need for the development of online and/or hyphenated techniques in ICP-MS. Microsampling combined with the separation of small amounts of analytes will be relevant for several chromatographic techniques (such as the development of micro- and nano-HPLC). There is a demand for further development of the combination of LA-ICP-MS as an element analytical technique with a biomolecular mass spectrometric technique such as MALDI- or ESI-MS for molecular identification and quantification of protein phosphorylation as well as of metal concentrations, this also enables the study of post-translational modifications of proteins, e.g. phosphorylation. 

Identification of the different types of ions observed in a mass spectrum through peak-matching and metastable ion analysis allows the determination of molecular structure. Several newer mass spectrometric techniques Mass analysed ion kinetic energy (MIKE) or reversed Nier-Johnson geometry) can also be used in spectral interpretation. These techniques are described in specialised monographs. 

Andrew G. Sharkey, Jr. Positive, negative, and neutral species have been found by probe techniques in flames. Direct mass spectrometric techniques should lead to identification of many of the primary species obtained by heating coal to extreme temperatures. 

As pointed out by Swisher and Prothero (1990) relatively recent advances (1989-1990) in mass spectrometric techniques and the development of laser-fusion 40Ar/39Ar dating techniques have resulted in the ability to date individual volcanic crystals, Multiple analysis and the ability to date single crystals allow the identification of multiplc-agc components due to detrital contamination, and thus permit improved precision and accuracy. To date, studies have been directed to North American chronology, notably minerals (biotite, anor, plag) found in Nebraska and Wyoming. 

Another technical challenge using the 2-DE-based approach relates to its narrow dynamic range of protein detection, a limitation that makes it almost impossible to detect and compare the expression of many very low abundance proteins, even with sample subfractionation. Though various aforementioned protein enrichment techniques are available, the application of LC-based protein separation coupled with highly sensitive mass spectrometric protein identification can address the issue of dynamic range, to a certain extent. This approach also improves the resolution and identification of proteins with extreme pi, large mass, and, in some cases, membrane associations. 

A possible solution to the above problems would be the triple-dimensional analysis by using GC x GC coupled to TOFMS. Mass spectrometric techniques improve component identification and sensitivity, especially for the limited spectral fragmentation produced by soft ionization methods, such as chemical ionization (Cl) and field ionization (FI). The use of MS to provide a unique identity for overlapping components in the chromatogram makes identification much easier. Thus MS is the most recognized spectroscopic tool for identification of GC X GC-separated components. However, quadru-pole conventional mass spectrometers are unable to reach the resolution levels required for such separations. Only TOFMS possess the necessary speed of spectral acquisition to give more than 50 spectra/sec. This area of recent development is one of the most important and promising methods to improve the analysis of essential oil components. 

As mentioned above in the context of the analysis of hgnin degradation products, gas chro-matography/mass spectrometry and related methods have been developed as extremely powerful tools for the identification of phenolic compounds. Use of high-pressure liquid chromatography in combination with mass spectrometry adds to the analytical arsenal with respect to the detection of polar, non-volatile compounds but, in particular, the advent of modem ionization techniques, such as ESI and MALDI mass spectrometry, have continued to broaden the analytically governable field of organic chemistry. The latter methods diminish the need of derivatization of polar phenolics to increase the volatility of the analyte. In this section, a more or less arbitrary selection of examples for the application of mass spectrometric techniques in analytical chemistry is added to the cases already discussed above in the context of gas-phase ion chemistry. 

Percent Abundance of Stable Products. The production and identification of stable products were accomplished by using Compartments A and C. Methane was radiolyzed with the intensity of EB-A sufficient to give about 1% decomposition with 100 e.v. electrons at a pressure of 10"2 torr in Compartment A. With Electrode 1 positive, the positive ions and neutral species produced in EB-A reacted as they diffused through the methane. We assume that only stable neutral products reached Compartment C where they were ionized by EB-C and analyzed by standard mass spectrometric techniques. The products and their percent abundances are given in Table HI. 

Hernandez F, Ibanez M, Sancho JV, Pozo OJ, Comparison of different mass spectrometric techniques combined with liquid chromatography for confirmation of pesticides in environmental water based on the use of identification points, Anal. Chem. 2004 76(15) 4349-4357. 

The efficient transfer of an analyte from its original condition to the ionization region of an ion mobility spectrometer (IMS) is the topic of this chapter. Snccessfnl detection and identification of an analyte by IMS depend on many steps but none more important than those by which a sample is introduced into an instrument. IMS instruments are used for the detection and identification of analytes found in air, water, biological fiuids and tissues, industrial solvents and on surfaces. Because ion mobility spectrometry is such a universal analytical instrument, sample introduction methods are diverse and depend on the type of sample analyzed. Atmospheric pressure operation makes IMS suitable for interfacing with several sample introduction systems as a detector as well as a selective filter for mass spectrometric techniques. 

Since the 1960s, mass spectrometry has played a pivotal role in the field of structure elucidation and identification of organic compounds. Over the years, a wealth of knowledge has been gained on reactions of gas-phase ions from the use of a variety of mass spectrometric techniques. Mass spectrometry can be used to identify unknown compounds or to perform de nova stmcture determination. The former is relatively easy if one knows accurate mass and a reference spectrum. The latter is much more difficult and requires detailed knowledge of the rules for interpretation of a mass spectrum. Providing this knowledge is the focus of this chapter. 

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