Solvent exchange treatment

Human adipose Addition of 13C-labeled standards to tissue followed by extraction with methylene chloride, acid-base washing, solvent exchange, treatment with silica gel impregnated with sulfuric acid, column chromatography using acidic silica gel, neutral alumina, and activated carbon addition of Relabeled standards. HRGC/HRMS (EPA Method 8290) 1 ppt No data EPA 1994c... 

Isolation. Isolation procedures rely primarily on solubiHty, adsorption, and ionic characteristics of the P-lactam antibiotic to separate it from the large number of other components present in the fermentation mixture. The penicillins ate monobasic catboxyHc acids which lend themselves to solvent extraction techniques (154). Pencillin V, because of its improved acid stabiHty over other penicillins, can be precipitated dkecdy from broth filtrates by addition of dilute sulfuric acid (154,156). The separation process for cephalosporin C is more complex because the amphoteric nature of cephalosporin C precludes dkect extraction into organic solvents. This antibiotic is isolated through the use of a combination of ion-exchange and precipitation procedures (157). The use of neutral, macroporous resins such as XAD-2 or XAD-4, allows for a more rapid elimination of impurities in the initial steps of the isolation (158). The isolation procedure for cephamycin C also involves a series of ion exchange treatments (103). 

A semi-interpenetrated network was obtained by bulk polymerization of 2-hydroxye-thyl methacrylate incorporated in DMF treated PET films by solvent-exchange technique, followed by treatment of films in e-lectrical discharges. Heparinization was accomplished by reacting glutaraldehyde with heparin and poly(2-hydroxyethyl methacrylate) present on the surface of modified polyester films. The immobilization of heparin was indirectly evidenced by chromatographying the silylated hydrolyza-tes of heparinized PET films and heparin, respectively. In vitro experiments demonstrated the enhanced thromboresistance of heparinized films. 

Following dialysis and treatment by SEC, the sample extracts were solvent exchanged into sterile DMSO. Subsequently, four rainbow trout Oncorhynchus mykiss [RBT]) were placed in each of seven tanks (each tank is considered as a treatment and a replicate is an individual fish within a tank) in 18 °C well water (280 mg hardness as CaCOs) using flow-through conditions. RBT were fed once daily throughout the study. Following a 48 hour acclimation, RBT were injected interperitoneally with 100 pL of a 1 1 mixture of an SPMD extract or appropriate controls in DMSO or corn oil. Controls included non-deployed SPMD extracts, SEC blanks, and DMSO blanks. The same injection procedure was repeated 6 days later. RBT were sacrificed 11 days after initial exposure to the extracts, and the plasma, liver, gills, and brain were immediately removed from each fish and maintained at -80 °C until assayed. 

Fig. 9.31 a) Synthesis of PS-b-polyacrylate brushes by LCSIP and consecutive ATRSIP [282]. AFM images of the tethered PS-fa-PMMA brushes with 23 nm thick PS layer and 14 nm thick PMMA layer b) after treatment with CH2CI2, c) with cyclohexane and d) after solvent exchange from CHjClj to cyclohexane, e) Cartoon proposing a model for the regular nanopattern morphology ( pinned micelles )... 

The scope of the 2-azadiene intramolecular Diels-Alder cyclization, employed for the synthesis of the daphniphyllum alkaloids, has been further investigated by Heathcock et al.[76j. The protocol involves Moffatt-Swem oxidation of the 1,5-diol to the dialdehyde, and treatment of the crude methylene chloride solution with ammonia followed by solvent exchange from methylene chloride to a buffered acetic add solution. The cydopentyl ring, quaternary carbon and tertiary carbon centers in... 

Solvent extraction is applied either directly to the weakly acidic leach hquor (the method is known as the Purlex process in South Africa, and the Amex process in the USA) or to the strongly acidic eluate obtained from a preliminary ion-exchange treatment of the leach liquor (known as the Bufflex process in South Africa, and the Eluex process in the USA). In the Purlex process, a 5 /(i solution of a tertiary amine in kerosene is typically used to treat a leach liquor containing up to 1 g of uranium per litre (although concentrations as low as 0.04 g 1 may be encountered) at a pH value of 1 to 2. A modifier such as isodecanol (2-5%) is usually incorporated into the organic phase to prevent the formation of a third phase and to inhibit the formation of an emulsion. The extraction of uranium(VI) is usually considered to proceed according to reactions such as ... 

Treatment of Sml2 with an equimolar amount of Na2[7,8-(C6H5CH2)2- Mfo-7,8-C2B9H9] in THF at room temperature accompanied by a solvent exchange from THF to DME gave the dark red dimeric complex [ (7,8-(C6HsCH2)2)- 7/o-7,8-C2B9H9 Sm(DME)2]2(DME) (Scheme 208).743... 

Many attempts have been made to rehne the ligand held treatment of substitution kinetics, and computer modeling of solvent exchange in particular (Section 8.7) has lately become almost a discipline in its own right, but there is as yet no panacea. The basic LFAE concept, however, does provide readily comprehensible qualitative... 

Lowering yiv may be effectuated by a solvent exchange, but because of the low permeability of the gel this treatment requires a long time to be achieved effectively. 

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