Mass spectrometer, first commercial

To overcome many of the limitations associated with PSD, several tandem TOF mass spectrometers (TOF/TOF) have been designed. Two of these tandem TOF mass spectrometers are commercially available, one sold by Applied Biosystems and the other by Bruker. The basic principle of these two instruments is to use a short linear TOF as the first mass... 

The combination of chromatography and mass spectrometry (MS) is a subject that has attracted much interest over the last forty years or so. The combination of gas chromatography (GC) with mass spectrometry (GC-MS) was first reported in 1958 and made available commercially in 1967. Since then, it has become increasingly utilized and is probably the most widely used hyphenated or tandem technique, as such combinations are often known. The acceptance of GC-MS as a routine technique has in no small part been due to the fact that interfaces have been available for both packed and capillary columns which allow the vast majority of compounds amenable to separation by gas chromatography to be transferred efficiently to the mass spectrometer. Compounds amenable to analysis by GC need to be both volatile, at the temperatures used to achieve separation, and thermally stable, i.e. the same requirements needed to produce mass spectra from an analyte using either electron (El) or chemical ionization (Cl) (see Chapter 3). In simple terms, therefore, virtually all compounds that pass through a GC column can be ionized and the full analytical capabilities of the mass spectrometer utilized. 

The thermospray interface overcame many of the problems enconntered with the moving-belt and direct-liquid-introdnction interfaces and with the advent of this, LC-MS became a routine analytical tool in a large number of laboratories. This was reflected in the fact that this was the first type of interface made available commercially by the majority of the mannfacturers of mass spectrometers. 

GC-C-IRMS was first demonstrated by Matthews and Hayes (1978). However, it was somewhat later that Barrie and others (Barrie et al., 1984) coupled a GC, via a combustion interface, to a dual collector mass spectrometer to produce the forerunner of today s GC-C-IRMS instruments. Even so, true determinations of 815N values of individual compounds by GC-C-IRMS remained elusive until finally demonstrated by Hayes and co-workers (Merritt and Hayes, 1994). More recently the precision of GC-C-IRMS instruments has been improved further still with uncertainties in 813C values as small as 0.5 %o for samples containing 5 pmol C and 0.1 %o for 100 pmol samples having been demonstrated (Merritt and Hayes 1994). Instruments available commercially today, from several manufacturers, all conform to the same general principles of design. 

The peak clue to molecular ion is referred as M+ peak and its mass corresponds to the molecular weight. The first analytical application of mass spectrometry was described in 1940 when mass spectrometers of good quality became commercially available. 

Gas chromatography was first coupled with a mass spectrometer in 1956 and GC/MS became commercially available in 1957 (de Hoffman and Stroobant, 2001). Examples of some of those applications pertinent to neurochemistry are listed in Table 6-1. 

Quadrupole mass spectrometers [10] or quadrupole ion traps are today the most widely used mass spectrometers. The physical bases were described in the early 1950s by Paul and Steinwedel. For his work Paul received the Nobel Prize in 1989 [11]. Triple quadrupole mass spectrometers have become very popular instruments for qualitative and quantitative analysis. Yost et al. [12] built in 1978 the first instrument and it took four years before this type of instrument was commercialized. The coupling with liquid chromatography or gas chromatography is well established and benchtop ion traps or quadrupoles are nowadays part of the standard equipment of many analytical laboratories. 

Magnetic sector ion microprobes are becoming increasingly important in isotopic analysis of extratenestrial materials as spot size decreases and the precision and accuracy of the measurements improve. The first of the commercially available ion microprobes used in cosmochemistry were the Cameca ims 3f-7f series machines, which initially became available in the mid-1980s. These multipurpose instruments are able to measure isotopic compositions of most elements of interest in cosmochemistry and can also be used to measure trace element abundances. Their main drawback is that the relatively small mass spectrometer can only be operated at mass-resolving powers below about 9000, and at this mass resolving power, the transmission of the mass spectrometer is very low. 

The Bendix Corporation s (USA) time-of-flight mass spectrometer (ToF-MS) with a pulsed electron impact ion source was one of the first commercial non-magnetic sector mass spectrometers on the analytical market as described by Wiley in 1956.37... 

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