High resolution applications

High resolution has three main applications. First, it allows determination of the molecular formula of a compound. From a given m/z ratio (to several decimal places), computer software suggests various possible molecular formulas. The better the resolution, the more decimals in the result. This in effect reduces the number 

Isotopic Abundances and Exact Masses of Main Isotopes of Elements Most Frequently Encountered in Molecules Analyzed by GC-MS 

Chemical Element Main Isotopes Isotopic Abundances (%) Exact Mass 

FIGURE 4.1 Chemical structures of polychlorobiphenyls, dioxins, and furans. 

Under the same principle, high resolution will also help detect a specific compound within a very complex mixture (essential oils, extracts of petroleum, wine, coffee) or from an extract containing many matrix interferents, where the probability of meeting co-eluted molecules supplying isobar ions is not negligible. To a certain extent, we can consider that the mass spectrometer will terminate the separation role of the chromatograph. 

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The HR column series was designed for high-resolution applications at higher pressures than the C, XK, or SR column series. Wetted materials include... 

Thome, G.C. Gaskell, S.J. Payne, P.A. Approaches to the Improvement of Quantitative Precision in SIM High Resolution Applications. Biomed Mass Spectrom. 1984,77,415-420. 

Martin, M. Z., Labbe, N., Andre, N., Harris, R., Ebinger, M., Wullschleger, S. D., and Vass, A. A. (2007). High resolution applications of laser-induced breakdown spectroscopy for environmental and forensic applications. Spectrochim. Acta Part B—Atomic Spectrosc. 62(12), 1426-1432. 

In general, in high resolution applications, the load of oligonucleotides applied to the column is a small fraction of the capacity of the column to bind oligonucleotides. As an example of the amounts which can be used Fig. 4.1. shows two isoplith separations ( 5.2.1) performed under identical conditions on 0.9 x 50 cm DEAE-cellulose columns. Increasing the load from 20-40 mg seriously affects the resolution of the main components. 

In developing API interfaces for FT-ICR-MS, one has to take account of the severe pressure restrictions in the ion cell a pressure of 10 Lpa is required for high-resolution applications. ESI FT-ICR-MS can be performed in two ways, i.e., with an external ion source in combination with a (quadmpole) ion guide, and with a probe mounted source which extends into the high field region. The first approach is more frequently applied. 

High-resolution applications of NMR in food science have been reviewed.26 Since the appearance of this review in 1984, the use of 2D NMR techniques has become commonplace, greatly increasing the power of NMR as a method for structural analysis of complex natural products, including many minor food components. In this section, however, attention will be given to quantitative rather than structural applications of high-resolution NMR. 

The need for an ever-increasing resolution in photolithography has resulted in an ongoing improvement of laser systems which have replaced UV lamp systems for high-resolution applications. The decrease of the irradiation... 

This review is focused on high-resolution applications and covers standard methods and some special techniques. Given the ease with which information can be found on the worldwide web, a review of available processing software turned out to be useless. 

It should be noted that although the separation of DNA can occur in dilute polymer solutions, semidilute solutions give better resolution than dilute ones. In dilute solutions, a narrow ratio of mobihty exists between small and large DNA fragments. Therefore, for high-resolution applications, semidilute solutions are preferred. However, if high resolution is not a necessity, dilute (and therefore less viscous) polymer solutions could be used, permitting easier... 

The laser projector is said to have infinite focus. To accomplish this, optics are necessary to keep the scanned laser beam thin. Such optics allow a video image to remain in focus from approximately 4 ft to infinity. For high-resolution applications, the focus is more critical. 

Another use of multilayer resists is in profile control. The PCM-type multilayer system is largely used for high-resolution applications with good linewidth control over complex geometries, but a further use of the multilayer system is in profile control. In this case isotropic etches are used which produce undercut or overcut profiles through suitable differential etch rates between layers. A common variant of this is two resists which are developed in mutually exclusive developers the control imparted by the multilayer system has found particular application for float-off metal deposition (Fig. 7.21). 

Availability of very fine threads for high resolution applications. 

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