Spectroscopic detection systems

For mechanistic study of reaction mechanisms various home-made reactors have been build. Variable reagent dosing and spectroscopic detection systems have been... 

ECL is also considered superior over other spectroscopic detection systems due to many distinct advantages [32], such as lack of a light source, the absence of a background optical signal, less sample volume, easy and simple instrumentation, precise control of reaction kinetics offered by controlling the applied potential, compatibility with solution-phase and thin-fihn formats, and opportunities to enhance intensity with nanomaterials such as metallic nanoparticles (NPs) and nanotubes (NTs), etc [33]. 

Figure 9 Liquid chromatography-RRS analysis of azo dyes. The spectra shown are for an 80-fjl. sample injection of 80 ppm eriochrome blue SE (EBSE). Spectra are collected with a 1-sec integration time at 4-sec intervals. (Reprinted with permission from CK Chong, CK Mann, TJ Vickers. Resonance Raman spectroscopic detection system for liquid chromatography. Appl Spec-trosc 46 249-254, 1992. Copyright 1992 Society for Applied Spectroscopy.)...

CK Chong, CK Mann, TJ Vickers. Resonance Raman spectroscopic detection system for liquid chromatography. Appl Spectrosc 46 249-254, 1992. 

CY Chen, MD Morris. Raman-spectroscopic detection system for capillary zone electrophoresis. Appl Spectrosc 42 515-518, 1988. 

Kinetic investigation of the reaction of cotarnine and a few aromatic aldehydes (iV-methylcotarnine, m-nitrobenzaldehyde) with hydrogen eyanide in anhydrous tetrahydrofuran showed such differences in the kinetic and thermodynamic parameters for cotarnine compared to those for the aldehydes, and also in the effect of catalysts, so that the possibility that cotarnine was reacting in the hypothetical amino-aldehyde form could be completely eliminated. Even if the amino-aldehyde form is present in concentrations under the limit of spectroscopic detection, then it still certainly plays no pfi,rt in the chemical reactions. This is also expected by Kabachnik s conclusions for the reactions of tautomeric systems where the equilibrium is very predominantly on one side. 

The most important area for packed column use involves modified mobile phases (MPs). Consequently, pSFC needs detection systems in which the MP modifier and possible additive(s) do not interfere, and in which detection of low or non-UV-absorbing molecules is possible in combination with pressure/modifier gradients. The disadvantage of adding even small amounts of modifier is that FID can no longer be used as a detector. In the presence of polar modifiers in pSFC the detection systems are restricted basically to spectroscopic detection, namely UVD, LSD, MSD (using PB and TSP interfaces as in LC). ELSD can substitute FID and covers the quasi-universal detection mode, while NPD and ECD cover the specific detection mode in pSFC on a routine basis. As ELSD detects non-UV absorbing molecules dual detection with UV is an attractive option. 

Several authors [386,387] have discussed the spectroscopic and nonspectroscopic (matrix) interferences in ICP-MS. ICP-MS is more susceptible to nonspectroscopic matrix interferences than ICP-AES [388-390]. Matrix interferences are perceptible by suppression and (sometimes) enhancement of the analyte signal. This enhanced susceptibility has to be related to the use of the mass spectrometer as a detection system. In fact, since both techniques use the same (or comparable) sample introduction systems (nebulisers, spray chambers, etc.) and argon plasmas (torches, generators, etc.), it is reasonable to assume that, as far as these parts are concerned, interferences are comparable. The most severe limitation of ICP-MS consists of polyatomic... 

Their structure and composition could be compatible with integrated detection systems, when used in solid phase spectroscopic measurements. 

Solvolytic reactions, medium effects on the rates and mechanisms of, 14, 1 Spectroscopic detection of tetrahedral intermediates derived from carboxylic acids and the investigation of their properties, 21, 37 Spectroscopic observations ofalkylcarbonium ions in strong acid solutions, 4, 305 Spectroscopy, 13C NMR in macromolecular systems of biochemical interest, 13, 279 Spectroscopy of substituted phenylnitrenes, kinetics and, 36, 255 Spin alignment, in organic molecular assemblies, high-spin organic molecules and,... 

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