Tandem mass spectrometry definition

The major advantage of the tandem mass spectrometry approach compared to MALDI peptide fingerprinting, is that the sequence information obtained from the peptides is more specific for the identification of a protein than simply determining the mass of the peptides. This permits a search of expressed sequence tag nucleotide databases to discover new human genes based upon identification of the protein. This is a useful approach because, by definition, the genes identified actually express a protein. 

Mass separator, 74 443 Mass spectrometer, 75 647-648, 650-665 Mass spectrometry (ms, MS), 75 647-670. See also Tandem mass spectrometry applications of, 75 666-669 archaeological materials, 5 743 biochemical, 75 666-668 concepts and definitions related to, 75 647-650... 

Keough T, Lacey MP, Fieno AM, Grant RA, Sun Y, Bauer MD, Begley KB. Tandem mass spectrometry methods for definitive protein identification in proteomics research. Electrophoresis 2000 21 2252-2265. 

Immunoassays may not be specific for the tested drug. Similar drugs may result in a positive test for example, pseu-doephedrine, present in cold medications, may produce a positive response in immunoassays designed to detect amphetamine and methamphetamine. Therefore it is imperative that positive screening tests be confirmed by an alternate, more definitive test. The most widely accepted method for drug confirmation is GC-MS. For further discussion of this technique, the reader is referred to Chapter 7. Liquid chromatography-tandem mass spectrometry is also used for rapid detection of drugs of abuse. 

This section is concerned with just one aspect of the relatively new development that has been termed in various ways such as mass separation/mass spectrometry or mass spectrometry/mass spectrometry (both offering the same acronyms MS/MS), two-dimensional mass spectrometry, tandem mass spectrometry, etc.. The acronym MS/MS is the most appropriate and is certainly the most widely used. The definitions and the nomenclature relevant to these techniques will be introduced as they will arise in our mathematical development of the scan laws. 

Tandem mass spectrometry provides a most definitive approach to protein identification. For tandem mass spectrometry, the work-up of proteins - typically by gel-based isolation and digestion - is exactly the same as for peptide mass fingerprinting. Also, the first dimension of mass spectrometry gives information practically identical to fingerprinting. However, the real power of tandem mass spectrometry is in product ion scanning. The molecular ions of... 

The aim of this chapter is to provide an overview of the instrumentation currently available for the mass analysis of MALDI ions. It is not intended as an exhaustive treahse on each instrument, and consequently if more detail is required the reader should examine the Usted reference material in detail. In the first sections of the chapter, the use of lasers for MALDI is discussed, and how they are coupled to the mass spectrometer, together with details of vibrational cooling and tandem mass spectrometry of MALDI ions. This is followed by a description of the different mass analyzer designs, with emphasis placed on commercially available instrument configurations. Definitions of aU acronyms, as well as technical descriptions of terms (such as peak centroid and resolving power) are included at the end of the chapter. 

In order to definitively establish that two fiber samples are of identical origin, it is i.a. necessary to demonstrate that their dye components are identical, and that those dyes are present in the same proportions in each fiber. The qualitative comparison is necessary because fiber manufacturers often use identical dyes in different proportions to create differently colored fibers. The combination of electrospray ionization mass spectrometry and tandem mass spectrometry has been shown to provide both the qualitative and quantitative information required such comparisons. The technique is sufficiently specific and sensitive to allow comparison of two fibers, one of which is available lengths of as little as one millimeter. The use of more sophisticated electrospray techniques (microspray and nanospray) would further enhance both specificity and sensitivity. 

The first part of this book is dedicated to a discussion of mass spectrometry (MS) instrumentation. We start with a list of basic definitions and explanations (Chapter 1). Chapter 2 is devoted to the mass spectrometer and its building blocks. In this chapter we describe in relative detail the most common ion sources, mass analyzers, and detectors. Some of the techniques are not extensively used today, but they are often cited in the MS literature, and are important contributions to the history of MS instrumentation. In Chapter 3 we describe both different fragmentation methods and several typical tandem MS analyzer configurations. Chapter 4 is somewhat of an outsider. Separation methods is certainly too vast a topic to do full justice in less than twenty pages. However, some separation methods are used in such close alliance with MS that the two techniques are always referred to as one combined analytical tool, for example, GC-MS and LC-MS. In effect, it is almost impossible to study the MS literature without coming across at least one separation method. Our main goal with Chapter 4 is, therefore, to facilitate an introduction to the MS literature for the reader by providing a short summary of the basic principles of some of the most common separation methods that have been used in conjunction with mass spectrometry. 

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