Ultraviolet-visible fluorescence

Takeuchi, S., and Tahara, T. 1998. Femtosecond Ultraviolet-Visible Fluorescence Study of the Excited State Proton Transfer Reaction of 7-Azaindole Dimer. J. Phys. Chem. A 102 7740. 

An early reference to the use of high performance liquid chromatography in the analysis of PAHs is the work of Jentoft and Gouw [183] and Vaughan et al. [184], These workers used ultraviolet, visible fluorescence detection and were able to detect 0.4ng of anthracene and 15ng of acenaphthalene. 

Analysis of Drugs in Preparations HPLC has found widespread use for the quantitative analysis of drugs in preparations of pharmaceutical and illicit manufacture. Drug concentrations are generally high enough to allow dissolution of the sample (tablet, powder, ointment, etc.) in a suitable solvent followed by injection. Ultraviolet-visible, fluorescence, or refractive index detection is normally used. 

The section on Spectroscopy has been retained but with some revisions and expansion. The section includes ultraviolet-visible spectroscopy, fluorescence, infrared and Raman spectroscopy, and X-ray spectrometry. Detection limits are listed for the elements when using flame emission, flame atomic absorption, electrothermal atomic absorption, argon induction coupled plasma, and flame atomic fluorescence. Nuclear magnetic resonance embraces tables for the nuclear properties of the elements, proton chemical shifts and coupling constants, and similar material for carbon-13, boron-11, nitrogen-15, fluorine-19, silicon-19, and phosphoms-31. 

The preceding empirical measures have taken chemical reactions as model processes. Now we consider a different class of model process, namely, a transition from one energy level to another within a molecule. The various forms of spectroscopy allow us to observe these transitions thus, electronic transitions give rise to ultraviolet—visible absorption spectra and fluorescence spectra. Because of solute-solvent interactions, the electronic energy levels of a solute are influenced by the solvent in which it is dissolved therefore, the absorption and fluorescence spectra contain information about the solute-solvent interactions. A change in electronic absorption spectrum caused by a change in the solvent is called solvatochromism. 

Once the analyte has been separated from the matrix in LC, the best approach to the detection of the molecule must be determined. This section will discuss the detection techniques of ultraviolet/visible (UVA IS), fluorescence (FL), and electrochemical (EC) detection, with MS being addressed separately in Section 4.2. When deciding on the most appropriate detector for an LC separation, the appropriate chemical data on the analyte should be collected by using a spectrophotometer, fluorimeter, and potentiometer. 

The principal limitation in the use of electrophoretic techniques is the lack of availability of suitable detection systems for quantitative analysis and unequivocal identification of pesticide analytes. Traditionally, either ultraviolet/visible (UVA IS) or fluorescence detection techniques have been used. However, as with chromatographic techniques, MS should be the detection system of choice. A brief comparison of the numbers of recent papers on the application of GC/MS and LC/MS with capillary elec-trophoresis/mass spectrometery (CE/MS) demonstrates that interfaces between CE... 

The output signal of concentration-sensitive detectors is proportional to the concentration or weight of polymer in the column eluent. Examples of this type include the differential refractometer and the ultraviolet-visible spectrophotometer. Infrared and fluorescence detectors are used infrequently. None of the detectors described above is truly universal i.e., the response of these detectors varies with the chemical species, and, in case of the DRI, response is also a function of the chromatographic eluent.156 Recently, an... 

Absorption ultraviolet-visible (UV-Vis) and fluorescence emission spectra of the aromatic pyrido[l,2-A]pyridazinium cation were measured in buffered aqueous solutions <2002MI37>. 

Fourier transform infrared (FTIR) spectroscopy, 13C nuclear magnetic resonance (NMR) spectroscopy, ultraviolet-visible (UV-VIS) and fluorescence spectroscopy can be integrated with chromatographic techniques especially in the study of ageing and degradation of terpenic materials. They can be used to study the transformation, depletion or formation of specific functional groups in the course of ageing. 

Finally, and apart from the importance of micelles in the solubilization of chemical species, mention should also be made of their intervention in the displacement of equilibria and in the modification of kinetics of reactions, as well as in the alteration of physicochemical parameters of certain ions and molecules that affect electrochemical measurements, processes of visible-ultraviolet radiation, fluorescence and phosphorescence emission, flame emission, and plasma spectroscopy, or in processes of extraction, thin-layer chromatography, or high-performance liquid chromatography [2-4, 29-33],... 

Ultraviolet/visible absorption, fluorescence, infrared and Raman spectroscopies are useful for studying structures (configuration, conformation, symmetry etc.) of electronically ground and excited states of linear polyenes, which have attracted much attention of... 

The ultraviolet-visible (UV-Vis) spectra of several isomeric pyrrolotetrazoles 12 and 13 in methanol have been compared. The spectra of ZH-pyrrolotetrazoles 13 are characterized by pronounced bathochromic shifts of the longest wavelength compared to those of 12 they also display green or blue fluorescence. The largest bathochromic shift for the 2/f-pyrrolotetrazole 13 (R1 = H, R2 = Ph, R3 = H, R4 = Ph) is ascribed to unhindered conjugative interaction of the phenyl group and the heterocycle, which is not possible to that extent for 12 (R1 = H, R2 = Ph, R3 = H, R4 = Ph) <2001J(P1)720>. 

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