Detector in mass spectrometry

Laprade, B.N. Labich, R.J. MicroChannel Plate-Based Detectors in Mass Spectrometry. Spectroscopy 1994,9,26-30. 

Electro-Optical Ion Detectors in Mass Spectrometry Simultaneous Monitoring of All Ions over Wide Mass Ranges... 

Just as it is almost impossible to represent a typical EGD-EGA apparatus, it is equally difficult to describe the wide variety of detectors that have been employed- Using the techniques listed in Table 8.2, the type of detector employed for each method is listed in Table 8.5. As can be seen, there are a number of different types of detectors used, from simple thermal conductivity detectors to more sophisticated ion current detectors in mass spectrometry. It is, of course, impossible to discuss each one in detail here, although the complete apparatus is described in certain cases. 

The detectors in mass spectrometry can be divided into two general types. One group is designed to detect one ion beam at a single location only (e.g.. Faraday cage, secondary ion multiplier), and the second group can detect several... 

There is potential confusion in the use of the word array in mass spectrometry. Historically, array has been used to describe an assemblage of small single-point ion detectors (elements), each of which acts as a separate ion current generator. Thus, arrival of ions in one of the array elements generates an ion current specifically from that element. An ion of any given m/z value is collected by one of the elements of the array. An ion of different m/z value is collected by another element. Ions of different m/z value are dispersed in space over the face of the array, and the ions are detected by m/z value at different elements (Figure 30.4). 

After adequate analitical prepai ation according to standai d EPA method 608 samples were analysed gas chromatographic on a gas chromatograph 8500 Perkin Elmer, in glass and capilar columns using a capture electron detector and mass spectrometry, temperature program. 

Figure 2.21. Schematic of (a) a photoplate detector (b) a Faraday cup (c) a discrete-dynode electron multiplier (EM) of Venetian blind type and (d) a continuous dynode EM. Parts (c) and (d) reprinted from A. Westman-Brinkmalm and G. Brinkmalm (2002). In Mass Spectrometry and Hyphenated Techniques in Neuropeptide Research, J. Silberring and R. Ekman (eds.) New York John Wiley Sons, 47-105. With permission of John Wiley Sons, Inc.

Eichelberger, J.W. and Budd, W.L. Studies in mass spectrometry with an ion trap detector. Finnigan MAT 47. 

Deflnition The sensitivity is the slope of a plot of analyte amount versus signal strength. In mass spectrometry, sensitivity is reported as ionic charge of a specified m/z reaching the detector per mass of analyte used. The sensitivity is given in units of C pg" for solids. [27] For gaseous analytes, it can be specified as the ratio of ion current to analyte partial pressure in units of A Pa . [28,29]... 

CEC is a miniaturized separation technique that combines capabilities of both interactive chromatography and CE. In Chapter 17, the theory of CEC and the factors affecting separation, such as the stationary phase and mobile phase, are discussed. The chapter focuses on the preparation of various types of columns used in CEC and describes the progress made in the development of open-tubular, particle-packed, and monolithic columns. The detection techniques in CEC, such as traditional UV detection and improvements made by coupling with more sensitive detectors like mass spectrometry (MS), are also described. Furthermore, some of the applications of CEC in the analysis of pharmaceuticals and biotechnology products are provided. 

P33 Analyses wereper/ormed on a gas chromatograph equipped with an electron capture detector (ECD) and a gas chromatograph coupled to a mass-selective detector working in mass spectrometry-mass spectrometry (MS-MS) mode, to achieve better limits of detection and selectivity. The proposed method yields high sensitivity, good linearity, precision, and accuracy. (From Dellinger et ah, 2001)... 

Organochlorine pesticides and OPPs have been determined mainly using GC, because of the stability and volatility that most of them show under chromatographic conditions and, particularly, the availability of element-selective detectors that display high selectivity for OCPs (electron-capture detector, ECD), and OPPs (flame photometric detector, FPD, and nitrogen phosphorus detector, NPD). Mass spectrometry-based detection is also more popular in GC than in HPLC (1,2,12,16). 

The more advanced instrumental methods of analysis, including GC, for the detection and identification of expls are presented (Ref 90) Pyrolysis of expls in tandem with GC/MS was used for the identification of contaminant expls in the environment (Ref 108). Isomer vapor impurities of TNT were characterized by GC-electron capture detector and mass spectrometry (Ref 61). Volatile impurities in TNT and Comp B were analyzed using a GC/MS the GC was equipped with electron capture and flame ionization detectors (Ref 79). The vapors evolved from mines, TNT, acetone, toluene, cyclohexanone and an organosilicon, were analyzed by GC/MS (Ref 78). Red water produced by the sellite purification of crude TNT was analyzed by GC/MS for potentially useful organic compds, 2,4-dinitrotoluene, 3- and 4-sulfonic acids (Ref 124). Various reports were surveyed to determine which methods, including GC/MS, are potential candidates for detection of traces of TNT vapors emitted from land mines factors influencing transportability of TNT vapors thru soil to soil/air interface are dis-... 

In mass spectrometry the sample is vaporized, and bombarded with electrons so that the molecules are ionized. The detector measures the mass/charge ratio, from which the molecular weight is determined and the molecule identified. Radicals often give the same fragment ions as the parent molecules, but they can be distinguished because lower energies are needed for the radical. 

G. Cavina, L. Valvo, B. Gallinella, R. Porra, and A. L. Savella, The identification of related substances in 9a-fluoroprednisolone-21 acetate by means of high-performance liquid chromatography with diode array detector and mass spectrometry, J. Pharm. Biomed. Anal., 79 437(1992). 

The various types of mass analysers will be discussed in this chapter with a description of their principles of operation. Because each type of analyser is based on significantly different principles, each has unique properties and specifications. The main characteristics of the different analysers presented in this chapter are summarized in Table 2.2. A description of the detectors used in mass spectrometry will also be given in Chapter 3. 

The ions pass through the mass analyser and are then detected and transformed into a usable signal by a detector. Detectors are able to generate from the incident ions an electric current that is proportional to their abundance. Detectors used in mass spectrometry were reviewed in 2005 [1]. The most common types of ion detectors are described below. Their specifications and their features are also discussed. 

These detectors are effective for most of the applications in mass spectrometry. Nevertheless, if a detector must ideally be free of any discrimination effect, its efficiency generally decreases when the mass of the ion increases. This induces limitations for the detection of high-mass ions and can compromise a quantitative analysis from these data because the signal decreases exponentially with increasing mass. On the other hand, progress in mass spectrometry has led to the advent of entirely new ionization sources and analysers that allow the study of analytes with very high molecular mass. For these reasons, the... 

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