Micelles enhancement

Howard [27] determined dissolved aluminium in seawater by the micelle-enhanced fluorescence of its lumogallion complex. Several surfactants (to enhance fluorescence and minimise interferences), used for the determination of aluminium at very low concentrations (below 0.5 pg/1) in seawaters, were compared. The surfactants tested in preliminary studies were anionic (sodium lauryl sulfate), non-ionic (Triton X-100, Nonidet P42, NOPCO, and Tergital XD), and cationic (cetyltrimethylammonium bromide). Based on the degree of fluorescence enhancement and ease of use, Triton X-100 was selected for further study. Sample solutions (25 ml) in polyethylene bottles were mixed with acetate buffer (pH 4.7, 2 ml) lumogallion solution (0.02%, 0.3 ml) and 1,10-phenanthroline (1.0 ml to mask interferences from iron). Samples were heated to 80 °C for 1.5 h, cooled, and shaken with neat surfactant (0.15 ml) before fluorescence measurements were made. This procedure had a detection limit at the 0.02 pg/1 level. The method was independent of salinity and could therefore be used for both freshwater and seawater samples. 

Solubilization of lipid digestion products in intestinal mixed micelles enhances their dissolution and dramatically increases the GI lumen-enterocyte concentration gradient that drives absorption by means of passive diffusion. Micelles, however, are not absorbed intact [8, 9], and lipids are thought to be absorbed from a monomolecular intermicellar phase in equilibrium with the intestinal micellar phase [10], The dissociation of monomolecular lipid from the micellar phase appears to be stimulated by the presence of an acidic microclimate associated with the enterocyte surface [11,12], In addition to passive diffusion, growing evidence suggests that active uptake processes mediated by transport systems located in the enterocyte membrane are also involved in the absorption of (in particular) fatty acids into the enterocyte [4],... 

The inhomogeneity of the micellar aggregate also affords assisted spin trapping and the exploitation of magnetic field effects on the charge separated ion pairs [48]. Optical modulation spectroscopy can be used, for example, to follow the decay of radicals formed in homogeneous solution and in SDS micelles. Enhancements of a factor of about 50 in the lifetimes and the steady state concentrations of the radical were observed in the micelle, and a kinetic analysis led to a value of 2 x 103 s 1 for the exit rate constant from the micelle [49]. 

The main advantage of paraceUular transport is the low proteolytic activity present in the paraceUular pathway. Lipid-surfactant mixed micelles enhance the... 

A method for determination of sodium isoascorbate (see 2) in boiler feed water, where it is used for deoxygenation, consists of following the reaction kinetics of Rhodamine B (13) in the presence of KBrOs, measuring at 555 nm. A linear correlation exists between the catalytic effect of the analyte on the reaction rate and its concentration Fe(III), Ca(II) and Mg(II) in the 5-200 ppm range interfere with the analysis . The effects of solvents, pH, surfactants, metal ions and other food additives on the absorbance were studied for the micelle-enhanced UV spectrophotometric determination of the food preservative sodium D-isoascorbate. The optimal conditions were using water at pH 7-8 as solvent and polyvinyl alcohol as surfactant, which causes an up to 3-fold increase of the UV absorbance. ... 

MICELLE ENHANCED FLUORIMETRIC DETERMINATION OF BENSERAZIDE IN PHARMACEUTICAL FORMULATIONS... 

Fig. 1. Fluorescence excitation (1) (Eem = 294nm) and emission (2) (E = 280nm) spectra of benserazide. Micelle-enhanced fluorescence excitation (3) (Eem = 318nm) and emission (4) (Eex = 279nm) spectra of benserazide, 1.0 x 10"4 M, pH 5.0, Triton...

Fig. 2. Calibration curve for benserazide obtained by micelle-enhanced fluorescence intensities as function of concentrations of benserazide. Aem 318 nm and pH 5.0.

M. Kato, M. Yamada, and S. Suzuki, Flavin Mononucleotide Sensitized and Polyoxyethylene (20) Sorbitan Trioleate Micelle-Enhanced Chemiluminescence for Sulfite Determination by Flow Injection Method [in Japanese]. J. Flow Injection Anal., 1(2) (1984) 31. 

Zn", and Co [10]. The amphiphilic ligands which were embedded in micelles enhanced the reachon rate in comparison with a dispersion in surfactant-free water. 

Saitoh K.., Hasebe T., Teshima N., Kurihara M. and Kawashima T. (1998) Simultaneous flow-injection determination of iron(II) and total iron by micelle enhanced luminol chemiluminescence. Analytica Chimica Acta, 376, 247-254. 

Pluronic poloxamers can be suitable carrier materials for this purpose due to their capacity to enhance the absorption of water-insoluble compounds by formation of micelles in aqueous environment that can host such hydrophobic compounds. Different authors have described the formation of quercetin-loaded Pluronic micelles by thin-film hydration methods and have shown that the resulting micelles enhanced the solubilization of the active compound. Ghanem et al. described the encapsulation of quercetin in Pluronic F127 via spray drying. ... 

Water pooled in reverse micelles enhances the rate of the imidazole catalysed hydrolysis of 4-nitrophenyl acetate. The rate of acylation of amines in apolar solvents is enhanced more by cationic micelles than by bis(2-ethylhexyl) sodium sulphosuccinate, and may be treated by the pseudophase model. ... 

Hinze, W. L., T. E. Riehl, H. N. Singh, and Y. Baba. 1984. Micelle-enhanced chemiluminescence and application to the determination of biological reductants using Lucigenin. Anal. Chem. 5 2180-2191. 

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