Double focussing instrumentation

The rate of loss of a methyl radical from the molecular ion of diethyl ether has been measured using a single-focussing mass spectrometer [42, 825]. The time resolution here was a few picoseconds. Loss of a methyl radical from the molecular ion of di-isopropyl ether has been investigated using a double-focussing instrument [743]. 

Double focussing instrumentation metastable ions sae observed at non-integer m/z values where there [Pg.262]

A novel HF-plasma SNMS instrument which can be combined with XPS has recently been developed [3.67]. Detection limits in the nmol/mol range have been achieved with a dedicated HF-plasma instrument attached to a double-focussing mass spectrometer [3.68]. 

Among other developments, a ikw collimator system composed of two double slits was designed and built at EMBL/DESY Using the double focussing X-ray EMBL instruments equipped with this collimator system, we obtained sharp, resolvable patterns with enhanced signal to noise ratio, and we were able to determine cell dimensions... 

A few years ago, we began a research program to develop methods of analysis which would involve the use of FAB and a high performance tandem mass spectrometer. The tandem instrument was the first triple sector mass spectrometer to be designed and built by a commercial instrument company (Kratos of Manchester, U.K.). The first mass spectrometer of the combination is a double focussing Kratos MS-50 which is coupled to a low resolution electrostatic analyzer, which serves as the second mass spectrometer U). This FAB MS-MS combination has been used to verify the structures of an unknown cyclic peptide (2), a new amino acid modified by diphtheria toxin (3), and an ornithine-containing lipid (4). A number of methods have also been worked out which rely on this instrumentation. They Include the structural determination of cyclic peptides (5), nucleosides and nucleotides (6), and unsaturated fatty acids (7) and the analysis of mixtures of both anionic (8) and cationic surfactants (9). 

Although there are many attractive features of Fourier transform mass spectrometry (FTMS), there are problems with current implementations. The FT mass spectrometer is still a relatively young instrument when compared to the double-focussing mass spectrometer, and comparisons of the spectrometers and their... 

Comparison with Sector Instruments. Modern double-focussing mass spectrometers have a long history of development, which was recently reviewed O) The instrument has evolved through a long series of complex and interweaving events beginning with the early experiments of J. J. Thomson (2) and the first mass spectrographs of... 

As already discussed above, Q-ICP-MS may still require matrix removal and preconcentration because the Q mass analyzer is unable to resolve most of the spectral interferences affecting the analytical masses of PGEs. Moreover, the detection power might be inadequate for the performance of reliable measurements in some samples. PGEs determination is hampered by mass interferences and requires high analytical selectivity and sensitivity. Double-focussing SF-ICP-MS with mass resolution capabilities higher than those afforded by Q instruments (currently up to 10,000) can properly deal with most mass interferences that have... 

In commercial instrumentation fairly low-cost quadrupole mass spectrometers and also expensive double-focussing sector field mass spectrometers are usually used (for a survey of mass spectrometers for analytical use, see Ref. [71]) and today new types of mass spectrometers such as time-of-flight mass spectrometers are being find utilized in plasma atomic spectrometry. 

Fig. 10.4 Scheme of a double-focussing magnetic sector instrument with BE configuration. Dependent on the mass-to-charge ratio the ions are distracted by the magnetic field to circular arcs with different radii. 

GC-HRMS (double focussing magnetic sector instrument) 0.15... 

Figure 2.191 The isotope pattern for 2,3,7,8-TCDD using a double focussing magnetic sector instrument with peak widths for resolutions of 1000 (a) and 10000 (b) (Furst and Berns-mann, 2010).

He/Ne laser focussed into a small tapered hole in a pellet of the plastic. The flux density achieved at the focus was about 1000 Watts/cma. The scattered radiation was examined using a double spectrometer and photon-counting detection. A very fine spectrum, superior even to that of Maklakov and Nikitin (see Table 1), was recorded photo-electrically. Schaufele pointed out that a band atAv= 109cm-1 forecast previously by Tadokoro et aL (15) was not observed at first but in a note added in proof he mentions that a feature may be genuine at 98 2 cm-1. A band had already been observed at Av= 110cm-1 by instrument developers at the Cary Instrument Co. since Szymanski (16) shows a spectrum of isotactic polypropylene, recorded at Monrovia, Calif., on a laser sourced Cary 81 spectrometer, as an example of recent advances in Raman spectroscopy. 

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