Fluorescence synchronous

Synchronous fluorescence spectra of all fractions were similar shown in Figure 3, but showed differences in relative intensity of four characteristic peaks at about 285,... 

Synchronous fluorescence has the potential to provide useful information regarding the relative abundance of protein-like vs. fulvic-like DOM (Peak I / Peak II) and humic-like vs. fulvic-like DOM (Peak Ill/Peak II). Figure 4 shows the... 

The EEM fluorescence allows identifying major differences in fluorescent properties between fractions. However, the EEM fluorescence spectroscopy may become very time-consuming. For quick preliminary analysis, it is recommended that synchronous fluorescence spectra be used for distinguishing samples of DOM with different chemical properties. 

Wakeham [14] has discussed the application of synchronous fluorescence spectroscopy to the characterization of indigenous and petroleum derived hydrocarbons in lacustrine sediments. The author reports a comparison, using standard oils, of conventional fluorescence emission spectra and spectra produced by synchronously scanning both excitation and emission monochromators. 

Derivative synchronous fluorescence spectrometry is a useful technique for the simultaneous determination of related species in mixtures with no prior separation as it combines the assets of derivative [99] and synchronous... 

Figure 18-21 Excitation and emission spectra of anthracene have the same mirror image relation as the absorption and emission spectra in Figure 18-16. An excitation spectrum is nearly the same as an absorption spectrum. [C. M. Byron and T. C. Wemer. Experiments in Synchronous Fluorescence Spectroscopy lor the Undergraduate Instrumental Chemistry Course"...

Experiments in Synchronous Fluorescence Spectroscopy for the Undergraduate Instrumental Chemistry Course," J. Chem. Ed. 1991,68,433.]... 

Pullin, M. J., and S. E. Cabaniss. 1997. Physiochemical variations in DOM-synchronous fluorescence Implications for mixing studies. Limnology and Oceanography 42 1766-1773. 

Cabaniss, S. E. 1992. Synchronous fluorescence spectra of metal-fulvic acid complexes. Environmental Science and Technology 26 1133. 

More detailed information about the fluorescence behavior of DOM can be reached by fractionation of the DOM before characterization. Studies from Chen et al. (2003) showed that the polyphenolic-rich DOM fraction exhibited a much more intense fluorescence and a red shift of peak position in comparison with the carbohydrate-rich DOM. Peuravuori et al. (2002b) used different anion exchange resins for the separation of DOM and synchronous fluorescence spectroscopy for characterization. They specified several classes of chromophores by the synchronous techniques Q,JKm 280/298,330/348,355/373,400/418,427/445,460/478,492/510, and 516/534nm). Fluorescene spectroscopy is also a sensitive method to distinguish between different sources of DOM. Examples for the different spectroscopic behavior of marine and terrestrial organic material is given by Lombardi and Jardim (1999). For several years, fluorescence spectroscopy has been used for qualitative... 

Murillo-Pulgarin et al. used a non-linear variable-angle synchronous fluorescence method for the simultaneous determination of dipyridamole and three other drugs that have potential for abuse by athletes [38]. The drugs studied (atenolol, propranolol, amiloride, and dipyridamole) were determined simultaneously at concentrations of KM100, 6-200, 5.6-280, and 5-100 ng/mL, respectively. Analyses were performed at 20°C in aqueous 70% ethanol at pH 7.5, adjusted with trishydroxymethyl... 

The use of second-derivative synchronous fluorescence spectrometry was reported by Ruiz et al. [42] to develop a simple, rapid and sensitive fluorimetric method for the determination of binary mixtures of the nonsteroidal antiinflammatory drugs flufenamic (FFA), meclofenamic (MCFA) and mefenamic (MFA) acids in serum and in pharmaceutical formulations. The method is based on the intrinsic fluorescence of these compounds in chloroform. A differential wavelength of 105 nm was used for the resolution of FFA-MFA and MFA-MCFA mixtures, whereas the FFA-MCFA mixture was determined at a differential wavelength of 40 nm. Serum samples were treated with trichloroacetic acid to remove the proteins, and the analytes were extracted in chloroform prior to determination. Pharmaceutical preparations were analyzed without prior separation steps. 

Sikorska, W. Gliszczynska-Swiglo, A. Khmelinskii, L Sikorski, M. 2005. Synchronous fluorescence spectroscopy of edible vegetable oils. Quantification of tocopherols. J. Agric. Food Chem. 53 6988-6994. 

Figure 8. Synchronous fluorescence (AA = 3nm) of (a) naphthalene (b) I-methylnaphthalene and (c) 2-methylnaphthalene...

Molecular fluorescence spectroscopy is a commonly employed analytical method that is sensitive to certain chemical properties of FA (9-13). Fulvic acid s molecular fluorescence is principally due to conjugated unsaturated segments and aromatic moieties present in the macromolecule (14). Several types of fluorescence spectra can be measured, including an excitation emission matrix or total luminescence spectrum, constant offset synchronous fluorescence, excitation spectra, and emission spectra, furnishing the researcher with useful data. The ability to resolve and select multiple fluorescent species makes these approaches extremely useful for studying FA relative to its chemical reactivity. 

Dissanayake A, Galloway TS (2004) Evaluation of fixed wavelength fluorescence and synchronous fluorescence spectrophotometry as a biomonitoring tool of environmental contamination. Marine Environmental Research 58 281-5. 

Giessing AMB, Mayer LM, Forbes TL (2003) Synchronous fluorescence spectrometry of 1-hydroxypyrene a rapid screening method for identification of PAH exposure in tissue from marine polychaetes. Marine Environmental Research 56 599-615. 

Fluorimetric measurements were carried out with a commercial Hitachi F-4500 spec-trofluorometer equipped with a 150 W xenon lamp and interfaced to a personal microcomputer for instrument operation and spectra processing. The slit-widths were adjusted at 2.5 nm both for excitation and emission and the photomultiplier (PMT R-3788) voltage set to operate at 950 V. The synchronous fluorescence spectra were corrected for variations with wavelength of the lamp intensity and photomultiplier sensitivity. 

Figure 4.3.6 Examples of front face synchronous fluorescence spectra obtained from tab-shaped (. s sorbent elements after immersion in Meuse River water spiked with a mixture of PAHs. The marked fluorescence bands are those that were used for measuring the concentrations of the individual PAHs...

Uziel M, Ward RJ, Vo-Dinh T. 1987. Synchronous fluorescence measurement of benzo(a)pyrene metabolites in human and animal urine. Anal Lett 20 761-776. 

Vahakangas K, Trivers G, Rowe M. et al. 1985. Benzo[a]pyrene diolepoxide-DNA adducts detected by synchronous fluorescence spectrophotometry. Environ Health Perspect 62 101-104. 

Spectroscopists have shown many powerful variations on the fluorescence experiment, which can generate additional selectivity and structural information. These include two-photon excitation (55) supersonic jet expansion (56) constant-energy synchronous fluorescence, where the excitation and emission monochromators are scanned synchronously to maintain a constant energy difference (57) and pulsed excitation for the real-time measurement of fluorescence lifetimes (58). However, it is far from certain that these techniques will ever be useful for the practicing analyst. 

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