Mass spectrometer An instrument that

Mass Spectrometer An instrument that measures the m/z values and relative abundances of ions. See also discussion in entry m/z. 

Mass spectrometer an instrument that generates ions and measures their mass-to-charge ratio (m/z) and their relative abundances. 

Mass spectrometer An instrument that measures the charge-to-mass ratios of charged particles. 

Mass spectrometer an instrument, such as one based on Thomson s principles, that measures the mass-to-charge ratios of atoms. (24)... 

Mass spectrometer (MS) An instrument that identifies substances by causing them to be ionized and subjecting the resulting ions to a strong electromagnetic field. 

In mass spectroscopy, sample molecules are ionized and the different masses of the ions formed are selected by use of an electric or magnetic field. In its simplest form, a mass spectrometer is an instrument that measures the mass-to-electric charge ratios of ions formed when a sample is ionized. If some of the sample molecules are singly ionized and reach the ion detector without fragmenting, then the mass-to-electric charge ratio of the ions gives a direct measurement of the weight of the molecule (de Hoffmann and Stroobant 2001). 

The dwelltime of ions within the ion source is defined by the extraction voltages applied to accelerate and focus them into an ion beam and by the dimensions of that ion source. In standard El ion sources the freshly formed ions dwell about 1 ps before they are forced to leave the ionization volume by action of the accelerating potential. [41] As the ions then travel at speeds of some 10 m s they pass the mass analyzer in the order of 10-50 ps (Fig. 2.9). [9] Even though this illustration has been adapted for a double focusing magnetic sector mass spectrometer, an ion of m/z 100, and an acceleration voltage of 8 kV, the effective time scales for other types of instruments (quadrupole, time-of-flight) are very similar under their typical conditions of operation (Table 2.4). 

To some of us it can unexpectedly happen that we are faced with the task of having to buy a mass spectrometer, eventually for ourselves or on behalf of someone else. References to certain commercial instruments made in this chapter were in no way intended to preclude such a 100,000-600,000 decision. The below guide may be useful in selecting an instrument that meets your requirements best ... 

The scope of the use of mass spectrometry in the protein analysis has grown enormously in the past few decades. MS has become an important analytical tool in biological and biochemical research. Its speed, accuracy and sensitivity are unmatched by conventional analytical techniques. The variety of ionization methods permits the analysis of peptide or protein molecules from below 500 Da to as big as 300 Da (Biemann 1990 Lahm and Langen 2000). Basically, a mass spectrometer is an instrument that produces ions and separates them in the gas phase according to their mass-to-charge ratio (m/z). The basic principle of operation is to introduce sample to volatilization and ionization source, and then the molecular fragments from the ionization of the sample are detected by various kinds of detector and the data are analyzed with computer software. 

A mass spectrometer is an instrument that separates particles by mass and measures their individual relative masses. If a nuclidic mass of an unknown compound is known with great precision from mass spectrometry, the exact molecular formula can often be deduced directly from this information without resort to a quantitative chemical analysis. 

The mass spectrometer is an instrument that is capable of separating particles of different isotopic composition and measuring their individual relative masses. The mass spectrometer also will pull a compound apart one atom at a time, producing fragments that can be detected by their specific masses. The distinction of various fragments and the level of precision in providing masses can supply information from which the exact molecular formula can be deduced without resorting to a quantitative chemical composition analysis. 

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