Residual gas analyser

Many applications of mass spectrometry do not require high resolution. Thus, other types of smaller, less expensive and lower performance mass spectrometers have been developed. Quadrupole mass filters that use an electric field to separate ions are in this category. These devices are used as mass detectors (GC/MS, LC/MS and ICP/MS) and in a variety of industrial processes for gas and residual gas analyses. 

Most residual gas analysers (RGAs) used routinely on vacuum systems are based on quadrupole mass spectrometers (see Figure 5.5). They have a mass range starting at 1 amu and ending at 100 amu. 

Chapter 5 considers the methods available for the measurement of both total and partial pressure in vacuum systems. For total pressure, the methods of measurement are described and, importantly, the uncertainty associated with that measurement is discussed. This may influence the choice of gauge. Also in Chapter 5, residual gas analysers (RGAs) for vacuum partial pressure measurements are described. These devices are being used increasingly for diagnostic work on vacuum systems. 

Pt/Alumina. A sample (0.5g) of 0.3% Pt/alumina EUROPT-3 was used to promote hexane to benzene conversion in a Micromeritics 2900 flow reactor system which permitted in-situ TPR, TPD, TPO and pulse hydrogen chemisorption etc. The exit stream from the reactor was analysed via a residual gas analyser and an FID gas... 

The terms mass spectrometry and mass spectroscopy are used synonymously because of the usage in another major field of application, the mass spectrometers used in the applications reviewed here are sometimes called residual gas analysers (RGA). 

Hulston J. R. and McCabe W. J. (1962) Mass spectrometer measurements in the thermal areas of New Zealand. Part I—Carbon dioxide and residual gas analyses. Geochim. Cosmochim. Acta 26, 383-398. 

The first commercial quadrupole mass spectrometers were developed as residual gas analysers (Quad 200 RGAs) by Bob Finnigan and P.M. Uthe at EAI (Electronic Associates Inc., Paolo Alto, California). 

A parallel detection to MS with a thermal conductivity detector is not found often in practice as the mass spectrometric analysis of gases is mostly carried out with specially configured MS systems (RGA, residual gas analyser, mass range <100 Da). Also, the parallel coupling of an FID does not lead to results which are complementary to those of MS, as both detection processes give practically identical total ion chromatograms. The response factors for most of the organic substances are comparable. A parallel MS detection to the FID can be used for a routine FID method development (see applications section). 

Residual gas analyser (RGA) Mass spectrometer used to measure the... 

Early quadrupole mass filters were very limited in mass range and resolution but their physical simplicity and the absence of a magnet made them attractive for upper atmosphere and space applications. Major development occurred in the 1960s inspired by this application. This same period also coincided with a rising demand for residual gas analysers because ultrahigh vacuum technology began to have routine... 

Getzendaner s method [199] for determining Dalapon (2,2 dichloropropionic acids is applicable to plant tissues and body fluid and doubtlessly to water samples. The sample was extracted with ethyl ether and the residue was analysed by gas chromatography on a glass column (1.2mx 2mm) of 4% LAC-2R plus 0.5% of phosphoric acid on Gas Chrom S (60-80 mesh) at 100°C with nitrogen as carrier gas (85mL min-1) and electron capture detection. Recoveries of about 90% were obtained for lOppm of the herbicide. 

In the experiments of Berthelot the gas analyses refer to the residual gas volume after the discharge has acted on the... 

SIMS requires clean ultra-high vacuum conditions to avoid contamination and reaction with residual gas components and normally has a relatively large analysed area. 

Residual-gas analysis (RGA), a mass-spectrometric method, is the most accurate method for measuring moisture and other low-molecular-weight volatile compounds released from polymeric materials. Interpretation of RGA data has at times proven difficult since small differences in the processing of samples intended to be identical resulted in major differences in the results and analyses of the same circuits by different laboratories. Most of these differences have been resolved by using laboratories that are certified by government agencies, such as Defense Supply Center at Columbus (DSCC), using their own standards. 

Nascent product state distributions have to be measured for a single photodissociation process, i.e., the products have to be analysed before they collide again with the residual gas. Otherwise the characteristic motion that emerges from the fragmentation process itself is changed by secondary collisions and the direct information about the fragmentation process is lost. 

Ultra-high vacuum conditions are important for two reasons. Firstly the material to be analysed is bombarded with particles or photons, and particles (electrons or ions) leaving the surface are detected these particles suffer collisions with residual gas molecules if the pressure is >10 torr. Secondly, and more important, surfaces to be analysed can be rapidly contaminated by adsorption of residual gas molecules if the pressure is >10 torr. Hence, surface-analysis instrumentation is constructed routinely to achieve 10 ° torr (after bake-out). 

The EPMA and the ESCA analyses suggest that oxygen impurities localized near the surface are due to the exposing air, while carbon impurities are incorporated in the films from a residual gas. 

The Isoprobe MC-ICP-MS (GV instruments, Wythenshawe, UK), a multi-collector device, is equipped with a pressurized hexapole collision cell to reduce the energy spread of the incoming ion before it enters the magnetic sector. Since it is a prerequisite that all ions must be accelerated by the same potential, all ions exit the hexapole at < 1 V potential and are then accelerated. The optional wide aperture retarding potential (WARP) filter is applied to enhance abundance sensitivity in this device. The WARP filter was originally developed for thermal ionization mass spectrometers in an attempt to improve the abundance sensitivity by two orders of magnitude. The principle of the WARP filter is that it excludes those ions that are not at the full accelerating potential. Any ions that have collided with residual gas molecules in the analyser are not transmitted by the WARP filter. 

Properties. The properties of naphtha, gas od, and H-od products from an H-coal operation are given in Table 7. These analyses are for Hquids produced from the syncmde operating mode. Whereas these Hquids are very low in sulfur compared with typical petroleum fractions, they are high in oxygen and nitrogen levels. No residual od products (bp > 540° C) are formed. 

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