Some Special Techniques

This section will deal with some special techniques that have been used to help solve some analytical spectroscopic problems. Some of the techniques described are used frequently and others occasionally. The section does not include every procedure that has been used but emphasizes some of the more important ones. 

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Dendrimers have been characterized by a variety of general techniques of analytical chemistry, and also by some specialized techniques that are particularly suitable for dendrimers. The following sections describe these techniques as they have been applied to dendrimers. For more details, the reader is referred to the books fisted in Further Reading section. 

The methods discussed above are suitable for simple and direct reactions where rates are simple power function of concentrations. These methods would not be helpful when the reactions are of complex nature and are occurring in multiple steps. The methods are also not applicable for the study of fast reactions where some special technique are required to be employed. 

In this method, the reaction is first allowed to attain equilibrium which is then disturbed in some way. The system approaches to attain a new equilibrium. The speed with which the system approaches its new equilibrium is followed using some special techniques. Let us consider a simple system... 

This review will first concentrate on the unimolecular gas-phase chemistry of diene and polyene ions, mainly cationic but also anionic species, including some of their alicyclic and triply unsaturated isomers, where appropriate. Well-established methodology, such as electron ionization (El) and chemical ionization (Cl), combined with MS/MS techniques in particular cases will be discussed, but also some special techniques which offer further potential to distinguish isomers will be mentioned. On this basis, selected examples on the bimolecular gas-phase ion chemistry of dienes and polyenes will be presented in order to illustrate the great potential of this field for further fundamental and applied research. A special section of this chapter will be devoted to shed some light on the present knowledge concerning the gas-phase derivatization of dienes and polyenes. A further section compiles some selected aspects of mass spectrometry of terpenoids and carotenoids. 

Carbon-13 NMR (13C-NMR) signals of aryl carbon atoms bonded directly to boron can be broad and/or low-intensity peaks. In some cases, they may not be observed, possibly depending on the quadrupolar relaxation rate of boron nuclei (79MI1) (Fig. 1). Some special techniques are known to increase the intensity of 13C signals of these carbon atoms (77JOM(132)29 78JOMC34). 

It is obvious that the special characteristic of fluoropolymers for NMR is the incorporation of the F nucleus, which is in many ways particularly suitable for study and can act as a unique probe to examine the chemical microstructure, domain structure and mobility at the molecular level for these materials. However, some special techniques are frequently required for the best results from F NMR of solid polymers. These are fully described in Section 6.6. The net result of the difficulties encountered in obtaining high-resolution solid-state F spectra is that relatively few research papers to date have reported spectra with optimised resolution. Therefore, most reported F... 

In polyurethane fabrication, some special techniques are used, such as prepolymer technique, quasiprepolymer technique and one shot technique. 

In this chapter common methods to evaluate chemical properties and phase composition of bioceramic coatings will be briefly described that are available in many laboratories including X-ray diffraction (XRD), vibrational spectroscopy techniques such as infrared (FTIR) and Raman spectroscopy and nuclear magnetic resonance spectroscopy (NMR). These methods provide a host of information on bulk phase composition, degree of crystallinity and crystallite size. Some special techniques including cathodoluminescence serve to reveal intrinsic coating properties that cannot be assessed by conventional analytical techniques, for example to distinguish between amorphous calcium phosphate (ACP) and crystalline calcium phosphates. 

A variety of experimental procedures can be used in a kinetic investigation. We will m.ention briefly some conventional methods first, then describe some special techniques. 

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. 

In this section we briefly discuss some special techniques of linear and nonlinear Raman spectroscopy that have particular advantages for different applications. These are the resonance Raman effect, surface-enhanced Raman signals, Raman microscopy, and time-resolved Raman spectroscopy. 

Some special techniques and possible applications of fast-ion-beam laser spectroscopy (FIBLAS) are illustrated by four different groups of experiments. 

Detection of immune responses to haptens is the same as that described above, but there are some special techniques now being used. A hapten-carrier complex can be prepared in vitro by combination in solution with a large protein such as albumin or a smaller molecule such as glutathione. These can then be used to coat a solid substrate. Alternatively, the protein carrier can be coated onto a substrate, the hapten added, and then the assay performed. This probably increases the amount of hapten that is available for antibody binding and minimizes that which is lost in the tertiary folding of the protein. 

Earlier, one of the perceived difficulties in the area of biotransformations was that of scale-up. Thus, while it seemed that test-tube experiments probably would be entirely feasible, the use of enzyme-catalysed processes on a kilogram scale or a tonne scale seemed a daunting task. It seems that, in many cases, those fears were unfounded, and the final chapter deals with some of the large-scale processes that have been industrial successes in terms of engineering and commerce. Because previously this topic has not been reviewed as extensively as the material described in Chapters 3-5, more detailed descriptions of the processes have been included. The latter part of the final chapter describes some special techniques of increasing importance in the field of biotransformations. 

Some specialized techniques may be used to identify a gemstone. Determining the gemstone s density can be very useful if the gemstone is not mixed with other minerals and is not mounted in jewelry. Gemologists might place the gem in a series of... 

Electrocatalysts for application in low-temperature fuel eells (ineluding PEMFCs and DMFCs) constitute a special type of heterogeneous eatalyst. The most important difference between an electrocatalyst and a normal heterogeneous catalyst is that the former should have good conductivity, whereas most typieal heterogeneous catalysts are insulators therefore, most characterization techniques for electrocatalysts are the same as for regular heterogeneous catalysts, but some special techniques are required for electrocatalysts because of their conductivity. ... 

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