Concentration, and partition

Isoxathion is extracted from plant materials with aqueous acetone. The extracts are concentrated and partitioned with n-hexane after addition of sodium chloride. The n-hexane phase is collected and concentrated after dehydration. The extract is partitioned with n-hexane and acetonitrile. The acetonitrile phase is collected, concentrated, and subjected to Horisil column chromatography. Isoxathion is eluted with diethyl ether-n-hexane after washing the column with the solvent. Isoxathion in the eluate is concentrated and dissolved in acetone and injected into a gas chromatograph for quantitative determination. 

Horowitz, A. and B J. Presley. 1977. Trace metal concentrations and partitioning in zooplankton, neuston, and benthos from the south Texas Outer Continental Shelf. Arch. Environ. Contam. Toxicol. 5 241-255. 

Monroe Wall of the USDA Eastern Regional Research Laboratory had been collecting plants for steroids that are oxygenated at positions 11 or 12, which could be converted into cortisone and related compounds. The search for a cancer cure led Wall to move to the Research Triangle Institute in 1960, to work on the isolation of plant-derived antitumor agents. Wall requested specimens of plants showing KB activity, and worked with a 30 lbs shipment of bark in late 1964. The procedure included extraction by ethanol, followed by concentration and partition between water and an organic solvent. He found that fractions from this extract were active in vivo for mice with... 

To an ice-cold suspension of Fmoc-Hyp-OH (lg, 2.83 mmol) in CH2C12 (50 mL) was added DAST (1.48 mL, 11.32 mmol). Upon dissolution, the soln was stirred for additional 5 h at rt, concentrated, and partitioned between EtOAc and 5% NaHC03. The aqueous layer was extracted with EtOAc, acidified with 5% NaHS04, and extracted with EtOAc. The extracts were washed with brine, dried (Na2S04), and taken to dryness yield 1 g (quant). 

Zhang, J.G, Huang, W.W., and Wang, Q. (1990) Concentration and partitioning of particulate trace metals in the Changjiang. Wat. Air Soil Pollut. 52, 57-70. 

A concentration referred to as thus equals the actual concentration of all forms of C02 in component j divided by K COz. This convention allows us to discuss fluxes in a straightforward manner, because C02 then diffuses toward regions of lower regardless of the actual concentrations and partition coefficients involved. For instance, to discuss the diffusion of C02 across a cell wall, we need to consider the partitioning of C02 between the air in the cell wall pores and the various types of C02 in the adjacent water within the cell wall interstices. Hence is the actual concentration of C02 plus H2CC>3, HCO3-, and CO32- in the cell wall water divided by the concentration of C02 in air in equilibrium with the cell wall water. 

A suspension of Trt-Ser(Trt)-OTrt (43.7 g, 52.5 mmol) in CHCI3 (80 mL), MeOH (25 mL), and AcOH (2mL) was warmed to 40 5 °C and stirred for 5-10 min until complete dissolution occurred. Then, the mixture was concentrated and partitioned between Et20 and 5% citric acid. The organic layer was washed with H2O. After addition of 1M NaOH, the sodium salt of ditrityl serine was filtered ofl) washed with IM NaOH, H2O, and Et20, and recrystallized (acetone) 5held 23.05 g (72%) mp 209 °C ... 

Dobson P. F., Skogby H., and Rossman G. R. (1995) Water in boninite glass and coexisting orthopyroxene concentration and partitioning. Contrib. Mineral. Petrol. 118, 414-419. 

Concentrations and partitioning of trace metals and relation to bioavailability... 

Fig. 8.2 Total concentrations and partitioning of Cd in a tidal flat sediment profile in the Heuckenlock areas near Hamburg. Sedimentation rates were determined using the Cs-method. Cadmium pore water profile was determined at low tide (Kersten 1989).

ScANCAE J, Miiacic R, Steazae M and Bueica O (2000) Total metal concentrations and partitioning of Cd, Cr, Cu, Fe, Ni and Zn in sewage sludge. Sci Total Environ 250 9-19. 

Pseudo-steady-state partitioning can take place in aquatic organisms immersed in an aqueous solution of toxicant or via exposure to vapor by inhalation through the lungs. The concentration of a toxicant at the narcosis site of action is a fxmction of both its aqueous concentration and partition coefficient. Increasingly lower aqueous concentrations are required to produce a common molar concentration at the site of action with increasing partition coefficient. These relationships are illustrated in Figure 2. 

Kozlov MY, Melik-Nubarov NS, Batrakova EV, Kabanov AV. Relationship between pluronic block copolymer structure, critical micellization concentration and partitioning coefficients of low molecular mass solutes. Macromolecules 2000 33 3305-3313. 

The dry roots of Pueraria lobata Ohwi (lOOg), collected in China, were extracted with water under heat. The extract was concentrated and partitioned between n-butanol and water. Evaporation of the organic layer gave a residue (15g). 

Zamadze, A. and L. A. Rodenburg. 2008. Water-column concentrations and partitioning of polybrominated diphenyl ethers in the New York/New Jersey Harbor, USA. Environ. Toxicol. Chem. 27(8) 1636-1642. 

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