Hydrophobic organic compound

In addition, the appHcation of the mass spectrometer (ms) as a detector for gas—Hquid chromatography has made the positive identification of peaks possible. High performance Hquid chromatography (hplc), which involves various detectors, can be used to measure hydrophilic and hydrophobic organic compounds in water. 

Ghoshal S, RG Luthy (1996) Bioavailability of hydrophobic organic compounds from nonaqueous-phase liquids the biodegradation of naphthalene from coal tar. Environ Toxicol Chem 15 1894-1900. 

Matter with Sorption Capacity for Hydrophobic Organic Compounds.125... 

Andren, A. W., Doucette, W. J., Dickhut, R. M. (1987) Methods for estimating solubilities of hydrophobic organic compounds Environmental modeling efforts. In Sources and Fates of Aquatic Pollutants. Hites, R. A., Eisenreich, S. J., Eds., pp. 3-26, Advances in Chemistry Series 216, American Chemical Society, Washington, D.C. 

Cho, H.-H., Park, J.-W., Liu, C.K. (2002) Effect of molecular structures on the solubility enhancement of hydrophobic organic compounds by environmental amphiphiles. Environ. Toxicol. Chem. 21, 999-1003. 

De Seze, G., Valsaraj, K.T., Reible, D.D., Thibodeaux, L.J. (2000) Sediment-air equilibrium partitioning of semi-volatile hydrophobic organic compounds. Part 2. Saturated vapor pressures, and the effects of sediment moisture content and temperature on the partitioning of polyaromatic hydrocarbons. Sci. Total Environ. 253, 27-44. 

Eadie, B.J., Morehead, N.R., Landrum, P.F. (1990) Three-phase partitioning of hydrophobic organic compounds in Great Lakes waters. Chemosphere 20, 161-178. 

Kan, A.T., Tomson, M.B. (1990) Ground water transport of hydrophobic organic compounds in the presence of dissolved organic matter. Environ. Sci. Technol. 9, 253-263. 

Georgi A, Trommler U, Reichl A, Kopinke F-D (2008) Influence of sorption to dissolved humic substances on transformation reactions of hydrophobic organic compounds in water. Part II hydrolysis reactions. Chemosphere 71 1452-1460... 

Poerschmann, J., Kopinke, F-D. (2001). Sorption of very hydrophobic organic compounds (VHOCs) on dissolved hymic organic matter (DOM). 2. Measurement of sorption and application of Flory-Huggins concept to interpret the data. Environ. Sci. Technol., Vol. 35, p. 1142. 

The major route for bioaccumulation of hydrophobic organic compounds in aquatic animals is passive diffusion over cell membranes. In fish, the gill epithelia are the predominant port of entry, with less than 40% of uptake across the skin [181]. Since permeability of the membrane is a direct function of the membrane-water partition coefficient and the diffusion coefficient across the membrane interior [182], the bioconcentration factor (logBCF) can be directly correlated with log K0Vl. or log Km%v for compounds with intermediate hydro-phobicity [183,184],... 

At concentrations above their aqueous solubility, the so-called c.m.c., low-molar-mass biosurfactants form micelles in the aqueous phase. Micelles are spherical or lamellar aggregates with a hydrophobic core and a hydrophilic outer surface. They are capable of solubilising nonpolar chemicals in their hydrophobic interior, and can thereby mobilise separate phase (liquid, solid or sorbed) hydrophobic organic compounds. The characteristics for the efficiency of (bio)surfactants are the extent of the reduction of the surface or interfacial tension, the c.m.c. as a measure of the concentration needed to bring about this reduction, and the molar solubilisation ratio MSR, which is the number of moles of a chemical solubilised per mole of surfactant in the form of micelles [96]. 

Micelles forming above the c.m.c. incorporate hydrophobic molecules in addition to those dissolved in the aqueous phase, which results in apparently increased aqueous concentrations. It has to be noted, however, that a micelle-solubilised chemical is not truly water-dissolved, and, as a consequence, is differently bioavailable than a water-dissolved chemical. The bioavailability of hydrophobic organic compounds was, for instance, reduced by the addition of surfactant micelles when no excess separate phase compound was present and water-dissolved molecules became solubilised by the micelles [69], In these experiments, bacterial uptake rates were a function of the truly water-dissolved substrate concentration. It seems therefore that micellar solubilisation increases bioavailability only when it transfers additional separate phase substrate into the aqueous phase, e.g. by increasing the rates of desorption or dissolution, and when micelle-solubilised substrate is efficiently transferred to the microorganisms. Theoretically, this transfer can occur exclusively via the water phase, involving release of substrate molecules from micelles, molecular diffusion through the aqueous phase and microbial uptake of water-dissolved molecules. This was obviously the case, when bacterial uptake rates of naphthalene and phenanthrene responded directly to micelle-mediated lowered truly water-dissolved concentrations of these chemicals [69]. These authors concluded from their experiments that micellar naphthalene and phenanthrene had to leave the micellar phase and diffuse through the water phase to become... 

DHS can significantly affect the environmental behavior of hydrophobic organic compounds and lower the possibility of direct contact of such organic compounds with various solid phases. The rate of chemical degradation, photolysis, volatilization, transfer to sediments/soils, and biological uptake may be different for the fraction of organic pollutant that is bound to DHS. If this is the case, the distribution and total mass of a pollutant in an ecosystem depends, in part, on the extent of humic matter-hydrophobic binding. 

Paschke, A. and Popp, P. 2003, Solid-phase microextraction fibre-water distribution constants of more hydrophobic organic compounds and dieir correlations widi octanol-water partition coefficients. J. Chromatogr. A 999 35-42. 

Although SPMDs concentrate a very wide range of hydrophobic organic compounds, they are not suitable for all environmental contaminants. Table 2.1 lists chemicals classes or selected compounds shown to concentrate in SPMDs, but is not all inclusive. 

Figure 2.4 Single compartment model for the uptake and release of hydrophobic organic compounds. The a/w subscript refers to air or water.

McCarthy, K.A. and Gale, R.W. 2001, Evaluation of persistent hydrophobic organic compounds in the Columbia River Basin using semipermeable membrane devices. Hydrol. Process 15 1271-1283. 

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