Fluorescence concentration

Decomposition of diphenoylperoxide [6109-04-2] (40) in the presence of a fluorescer such as perylene in methylene chloride at 24°C produces chemiluminescence matching the fluorescence spectmm of the fluorescer with perylene was reported to be 10 5% (135). The reaction follows pseudo-first-order kinetics with the observed rate constant increasing with fluorescer concentration according to = k [flr]. Thus the fluorescer acts as a catalyst for peroxide decomposition, with catalytic decomposition competing with spontaneous thermal decomposition. An electron-transfer mechanism has been proposed (135). 

Chen, R.F., and Knutson, J.R. (1988) Mechanism of fluorescent concentration quenching of carboxyfluo-rescein in liposomes Energy transfer to nonfluorescent dimers. Anal. Biochem. 172, 61. 

It may be useful to introduce impermeant fluorocromes without micro-injection. Permeabilization is suitable for small to medium cells. Large cells (e.g., Chara ) can be permeabilized osmotically (46) and become permeable to the fluorescent analogue of ATP, e-ATP (46). Vacuolar compartmentation still occurs, but the cell wall is porous to molecules of only 4158 Dalton (approx 4.8 nm). Internal fluorescence concentration increases only slowly because of the large volume of cytoplasm. 

To avoid reabsorption problems and thus low-emission intensities, the fluorescer concentration should not exceed 10 A/. Typically the fluorescer concentration range is taken between 10 to 10 A/for the double reciprocal plot. Should it be necessary to work at much higher fluorescer concentration, correction for reabsorption is essential. This is readily done by measuring the fluorescer emission intensity as a function of pathlength. From a plot of fluorescer emission intensity vs. path-length one extrapolates /pf at zero pathlength and applies the necessary correction. 

On oxidation, homovanillic acid, HVA (4-hydroxy-3-methoxy-phenyl-acetic acid), is converted to a highly fluorescent, stable compound with an excitation wavelength of 315 nm and an emission wavelength of 425 nm. Oxidized HVA is produced in an amount proportional to that of GOase between 0.001 and 0.25 U/ml (Guil-bault, 1968). Guilbault (1976) showed that p-hydroxyphenylacetic acid has some advantages over HVA with respect to cost and fluorescence coefficient (fluorescence/concentration) and 0.01 U of enzyme could be assayed. 

Electronic excitations in molecular aggregates have received considerable attention from theoretists and experimentalists in recent years. Much of the work has focused on excitonic transport in molecular crystals (J.), in sub s t i t u 11 o na 11 y disordered mixed crystals (2.) and in amorphous structures (3.). Furthermore, excitation energy transfer (EET) has been studied in fluorescence concentration depolarization of donor molecules in solution (4.) as well as in excited-state energy transfer of donor -acceptor dyes in condensed phase systems (5.). 

In the intrinsic case, the analyte itself is the fluorescent concentration, where its concentration can be determined using the Parkers Law... 

Fig. 5 Fluorescence-concentration plot illustrating nonlinear relation at the extremes of concentration.

Cover design Image of an odor plume taken using planar, laser-induced fluorescence Concentration of the odor in the plume indicated by color. From Crimaldi etal., J. Turbul. 3 1-24, 2002. Reproduced with the permission of the authors and Taylor and Francis. (Chapter 8)... 

Five superwarfarin rodenticides (chlorophacinone, bromadiolone, difetfaialone and cis- and tmn.rextracted from serum and separated on Cg column (2 = 285 nm or 265 nm, ex 400 nm, em). Very good peak shapes were generated with a 45/25 acetonitrile/water (20 mM acetate buffer at pH 4.7 with 1 mM tetrabutylammonium hydroxide) mobile phase [978]. Detection limits for UV were 20-75 ng/mL, whereas for fluorescence Aey were 3-l2ng/mL (however, chlorophacinone and difethialone did not fluoresce). Concentration curves were linear from 100 to 1000 ng/mL. 

Fluorometric fiber optics fluorescing concentration of enzyme substrates/products or immunolabels enzyme and bioaffinity reactions... 

Goldschmidt, J.C., Peters, M., Bosch, A., Helmers, H., Dimroth, F., Glunz, S.W., and Willeke, G. (2009) Increasing the efficiency of fluorescent concentrator systems. Sol Energy Mater. Sol Cells,... 

Gombert, A., Glunz, S., Willeke, G., and Rau, U. (2008) Theoretical and experimental analysis of photonic structures for fluorescent concentrators with increased efficiencies. Phys. Status Solidi(a), 205, 2811-2821. 

Chen RF, Knutson JR (1988) Mechanism of fluorescence concentration quenching of car-boxyfluorescein in liposomes energy transfer to nonfluorescent dimers. Anal Biochem 172(l) 61-77... 

Syntheses of different types of latex particles by emulsion polymerization that differ in particle size, polymer hydrophificity, and surface coverage with functional groups were presented by Paulke et al. [51 ]. The particles were equipped with intensive fluorescence. Concentrated particle suspensions were injected into the brain tissue of mice and the effect of two kinds of beads is shown in brain sections. The same research group [52] presented a very different work on electrophoretic three-dimensional (3D)-mobility profiles of latex particles with different surface groups. In particular, hydroxyl functions were studied in different surroundings. The latexes gave model colloids with different electrophoretic behavior in comparison with classical anionic monodisperse PS latex particles. 

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