Dissolved fluorescent substances

Kramer, C.J.M., 1979. Degradation by sunlight of dissolved fluorescing substances in the upper layers of the Eastern Atlantic Ocean. Neth. J. Sea. Res., 13 325—329. 

Schlautman, M.A., Morgan, JJ. (1993b) Binding of a fluorescent hydrophobic organic probe by dissolved humic substances and organically-coated aluminum oxide surfaces. Environ. Sci. Technol. 27, 2523-2532. 

In lakes, the pool of dissolved organic carbon (DOC) is dominated by dissolved humic substances (up to 80% of the DOC). Lake humic substances are similar to soil humic substances in that carboxyl, hydroxyl, phenol, and probably methoxyl groups are of major significance. Fluorescence spectra of DOC may be interpreted in terms of the different geochemical origins of DOC (e.g., allochthonous versus algal derived). One or more moieties of dissolved humic substances are produced autochthonously mechanisms may include polymerization of phenols (promoted by transition metals), Maillard condensations, or oxidation via phenolase systems. Aliphatic structural units in dissolved humic substances provide a flexible conformation to the humic substance molecule. ... 

Despite these limitations, there are advantages of fluorescence measurements of dissolved humic substances. For example, Ghosh and Schnitzer (1980a) were able to differentiate between soil fulvic acids and humic acids, since fulvic acids exhibited additional excitation bands at 360 nm. Further studies are needed to reveal if this phenomenon also occurs in freshwater humic substances. 

The same applies to fluorescent substances. These dissolve in the hydrophobic... 

Samples for liquid scintillation counting consist of three components viz. (1) the radioactive material, (2) a solvent, usually aromatic, in which the radioactive substances is dissolved or suspended, and (3) one or more organic fluorescent substances. Components (2) and (3) make up the liquid scintillation system. The P particles emitted from the radioactive sample (most of the radioisotopes used in biochemical research are P emitters) interact with the scintillation system, producing small flashes of light or scintillations. The light flashes are detected by a photomultiplier tube (PMT). Electronic pulses from the PMT are amplified and registered by a counting device called a scaler. 

Hydrochloride, Cl3H. CLNj, Monacrin, Acramine Yellow Pale yellow crystals. Neutral reaction, One of the most highly fluorescent substances. One gram dissolves in 300 ml water giving a faintly yellow soln showing bluish-violet fluorescence. LDm orally in mice 78 mg/kg, D, C, Brodie, E. Lowenhaupt, J. Am. Pharm, A soc 38, 498 (1949). 

Purification of anthracene. Dissolve 0-3 g. of crude anthracene (usually yellowish in colour) in 160-200 ml. of hexane, and pass the solution through a column of activated alumina (1 5-2 X 8-10 cm.). Develop the chromatogram with 100 ml. of hexane. Examine the column in the hght of an ultra-violet lamp. A narrow, deep blue fluorescent zone (due to carbazole, m.p. 238°) will be seen near the top of the column. Immediately below this there is a yellow, non-fluorescent zone, due to naphthacene (m.p. 337°). The anthracene forms a broad, blue-violet fluorescent zone in the lower part of the column. Continue the development with hexane until fluorescent material commences to pass into the filtrate. Reject the first runnings which contain soluble impurities and yield a paraffin-hke substance upon evaporation. Now elute the column with hexane-benzene (1 1) until the yellow zone reaches the bottom region of the column. Upon concentration of the filtrate, pure anthracene, m.p. 215-216°, which is fluorescent in dayhght, is obtained. The experiment may be repeated several times in order to obtain a moderate quantity of material. 

Mayer, L.M., Schick, L.L., Loder, T.C. 1999. Dissolved protein fluorescence in two main estuaries. Marine Chemistry, 64, 171-179. Miano, T.M., Senesi N., 1992. Synchronous excitation fluorescence spectroscopy applied to soil humic substances chemistry. Sci Total Environ, 117/118, 41-51. 

Uchiyama [11] applied this method to the determination of fluorescent whitening agents and alkyl benzenesulphonates and also methylene blue active substances in bottom sediment samples taken in a lake. The muds were filtered off with a suction filter and frozen until analyzed. About 20g of wet bottom mud was extracted three times with a methanol-benzene (1 1) mixture. After the solvent was evaporated using a water bath, the residue was dissolved in hot water and this solution used for analysis. Table 10.2 shows the analytical results for methylene blue active substances (MBAS), alkyl benzene-sulphonate (ABS), and fluorescent whitening agent (FWA) in bottom sediments. 

Pure ionic liquids (ILs) are solvents that remain colorless and transparent throughout almost the whole visible and near-infrared (NIR) spectral regions. This property coupled with excellent stability makes ILs very attractive optical solvents that may be used for the absorption and fluorescence studies of dissolved substances, as well as for monitoring the reactions... 

Exercise 28-3 The fluorescence of many substances can be quenched (diminished or even prevented) by a variety of means. Explain how concentration, temperature, viscosity, and presence of dissolved oxygen and impurities may affect the degree of fluorescence observed for solutions of a fluorescent material. Would you expect similar effects on phosphorescence Explain. 

Equilibrium dialysis is used in a number of examples to analyse the ratio of lipid-bound to free analyte. Kramer et al. (1998) described the use of equilibrium dialysis by separating the liposome suspension and the water phase by a semi-permeable membrane. The analyte is dissolved in the water compartment of the system and diffuses into the liposome compartment. If equilibrium is reached, the remaining concentration of the analyte in the water compartment is determined by means of a quantification method (mainly HPLC or LCMS, fluorescence techniques) and the partition coefficient is calculated. Kramer et al. (1997) used a radio tracer substance as analyte to quantify the compound in both compartments using liquid scintillation counting. 

Radium Barium Platinocyanide.—-Since the majority of platino-cyanides fluoresce under the influence of radiations from radioactive substances, the radium salt should be self-luminous. The radium barium salt was prepared1 by dissolving radioactive barium chloride in water and boiling the solution with excess of silver platinocyanide. After filtering off insoluble silver salts the solution was allowed to crystallise in a desiccator. 

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