Extractants combinations

Soil samples have been found to contain 500 ppm of TCE and 750 ppm of benzene. Two technologies are being considered to remediate the soil. One is based on vapor extraction combined with carbon adsorption. The other technique is simply to inject steam into the ground, vaporize the solvents and then withdraw them as a vapor extraction technique, discharging the... 

Figure 2.19 Schematic representation of an on-line liquid-liquid extraction-GC/AED system. Reprinted from Journal of High Resolution Chromatography, 18, E. C. Goosens et al, Continuous liquid-liquid extraction combined on-line with capillary gas chromatography- atomic emission detection for environmental analysis , pp. 38-44, 1995, with permission from Wiley-VCH.

Immunoaffinity extraction combined on-line with LC in conjunction with MS (108 -110) or tandem MS (111, 112) has also been demonstrated for the determination of analytes in biological fluids. Obviously, such systems offer a very high... 

Y. Hirata and Y. Okamoto, Supercritical fluid extraction combined with microcolumn liquid chromatography for the analysis of polymer additives , J. Microcolumn Sep. 1 46-50(1989). 

There is a great number of separation and purification processes to choose from in process development, but classical separations such as crystallization, filtration, drying, liquid-liquid extraction and distillation are still predominantly used. For solid products crystallization, filtration, and drying are the first options although vacuum distillation and extraction combined with the other techniques are also possible. For liquid products, liquid-liquid... 

The methods EN 1528 1996 and EN 12393 1998 comprise a range of old multiresidue methods of equal status, which are widely accepted throughout Europe. These are, e.g., the Luke method and the German Deutsche Forschungsgemeinschaft (DFG) methods S8 and S19 ° (all based on extraction with acetone), the Association of Official Analytical Chemists (AOAC) method 970.52 (using acetonitrile extraction and liquid-liquid partition combined with Horisil column cleanup) and the Dutch ethyl acetate extraction combined with GPC. All methods have been subjected to inter-laboratory studies, although not with all pesticide/matrix combinations, which would be impossible to achieve. 

Riel [67] studied in situ extraction combined with y-ray spectrometry in an underwater probe for the determination caesium and chromium in seawater. 

Bourgogne E., Grivet C., and Hopfgartner G., 2005. Determination of talinolol in human plasma using automated online solid phase extraction combined with atmospheric pressure chemical ionization tandem mass spectrometry. J Chromatogr B 820 103. 

Zhou S. et al., 2005. High-throughput biological sample analysis using online turbulent flow extraction combined with monothic column liquid chromatography/tandem mass spectrometry. Rapid Commun Mass Spectrom 19 2150. 

Fernandez et al. [9] used supercritical fluid extraction combined with ion pair liquid chromatography to determine quaternary ammonium in digested sludges and marine sediments. Carbon dioxide modified with 30% methanol was used as the extractant at an operating pressure of 380atm. Between 0.2 and 3.7g kg-1 surfactant was found in Swiss works effluent sludges, determined with a relative standard deviation of 7%. 

Acetic acid is an important intermediate organic tonnage chemical that may be produced by the petroleum industry and fermentation. The latter process requires the recovery of acetic acid from water solutions, and several techniques have been applied to this separation, including solvent extraction, azeotropic distillation, and extractive distillation. A comparison of economics between azeotropic distillation and solvent extraction combined with azeotropic distillation (Table 10.3) shows that the introduction of... 

Mix 230 ml of dry ethanol with 32.5 g of sodium methoxide under a nitrogen atmosphere until the methoxide is dissolved. Add 110 g of diethyl malonate and stir for 10 min, then add 75 g of 3-nonene-2-one (or equimolar amount of 5,6-dimethylundec-3-ene-2-one for dimethyl-heptyl) keeping the temp below 49° with external cooling. Stir and reflux for 3 hours, cool to room temp, neutralize with coned HCL add (about 45 ml), and let stand for 8-12 hours. Evaporate in vacuo, and dissolve the residue in 1 N HCl acid and 800 ml ethylacetate. Allow to stand to separate the ethyl acetate, then wash it (the acetate) with two 300 ml portions of water and extract with a saturated solution of NaHCOs until a small sample shows no turbidity upon acidification (it will take at least nine 100 ml portion extractions). Combine the NaHCOs extractions and very carefully acidify them with tiny portions of acid. Extract with three 300 ml portions of ether, and remove the ether by evaporation in vacuo after drying with MgS04 to get the methyl-carboxylate. 

Extracts (12 mL each) were added to Petri dishes 10 cm in diameter containing 50 g of 30-mesh washed sand covered with filter paper circle (7-cm diameter, Whatman 1). Controls were moistened with doubly distilled water. Ten indicator seeds were placed on the filter paper in each dish with the embryo down and the hypocotyl pointed to the center of the Petri dish. Each indicator/extract combination had 3 replicates. The Petri dishes were kept in a dark growth chamber for approximately 72 hr at 25°C. The radicle length of each germinated seedling was measured at 72 hr. 

I. 4-methoxyacetophenone (30 //moles) was added as an internal standard. The reaction was stopped after 2 hours by partitioning the mixture between methylene chloride and saturated sodium bicarbonate solution. The aqueous layer was twice extracted with methylene chloride and the extracts combined. The products were analyzed by GC after acetylation with excess 1 1 acetic anhydride/pyridine for 24 hours at room temperature. The oxidations of anisyl alcohol, in the presence of veratryl alcohol or 1,4-dimethoxybenzene, were performed as indicated in Table III and IV in 6 ml of phosphate buffer (pH 3.0). Other conditions were the same as for the oxidation of veratryl alcohol described above. TDCSPPFeCl remaining after the reaction was estimated from its Soret band absorption before and after the reaction. For the decolorization of Poly B-411 (IV) by TDCSPPFeCl and mCPBA, 25 //moles of mCPBA were added to 25 ml 0.05% Poly B-411 containing 0.01 //moles TDCSPPFeCl, 25 //moles of manganese sulfate and 1.5 mmoles of lactic acid buffered at pH 4.5. The decolorization of Poly B-411 was followed by the decrease in absorption at 596 nm. For the electrochemical decolorization of Poly B-411 in the presence of veratryl alcohol, a two-compartment cell was used. A glassy carbon plate was used as the anode, a platinum plate as the auxiliary electrode, and a silver wire as the reference electrode. The potential was controlled at 0.900 V. Poly B-411 (50 ml, 0.005%) in pH 3 buffer was added to the anode compartment and pH 3 buffer was added to the cathode compartment to the same level. The decolorization of Poly B-411 was followed by the change in absorbance at 596 nm and the simultaneous oxidation of veratryl alcohol was followed at 310 nm. The same electrochemical apparatus was used for the decolorization of Poly B-411 adsorbed onto filter paper. Tetrabutylammonium perchlorate (TBAP) was used as supporting electrolyte when methylene chloride was the solvent. 

Echinacea products provide an example of the large variation in manufactured products. The whole plant has been used for therapeutic purposes, but single-entity product can consist of E. purpurea herb extracts, combination... 

In some instances, combinations of normal- and reversed-phase columns can also be used for better purification of the crude extract. Combinations of Ci8 and alumina or Cig and silica solid-phase extraction columns have been successfully employed in the analysis of ivermectin residues in animal tissues (346) and bovine plasma (348), respectively. Elimination of coextracted materials and concentration of the analytes has also been accomplished using mixed-phase extraction columns. Such a copolymeric bonded silica column with both hydro-phobic and cationic functions has been employed in the analysis of hygromycin B in plasma, serum and milk (326). 

Drinking water solvent extraction (combination) cytotoxicity, promotion 40... 

When, however, an extraction, or an extraction combined with a chemical reaction, is carried out between two phases in a continuous stirred tank reactor in which there is no interaction occurring between the dispersed particles (complete segregation), the dispersed particles will have different concentrations because of the spread in residence time. Any kind of interaction between the dispersed particles (e.g., by diffusion or by continuous coalescing and redispersion) then tends to eliminate these concentration differences. 

In this chapter some effects of segregation on the kinetics of a chemical reaction between two liquid phases carried out in a continuous stirred tank reactor (CSTR) will be discussed. In the derivations of these effects it will be assumed that during the reaction the dispersed phase is maintained (e.g., in the case of extraction combined with chemical reaction) and that all dispersed drops have the same size. This means that when there is segregation it is only the age distribution which causes a concentration distribution in the dispersed phase. 

Phenyl selenide, CeHg.SeH.1—This selenide may be obtained as follows (1) Selenium tetrachloride is allowed to react with benzene in the presence of aluminium chloride. (2) Magnesium phenyl bromide in ether solution is treated with finely divided selenium and the addition product treated with cold hydrochloric acid. The ether layer is then removed, the extracted solution treated with more ether and the extracts combined, then shaken with one equivalent of sodium hydroxide, calculated on the basis of the total amount of selenium used, and dissolved in water to make a 25 per cent, solution. The ether solution is then dried with calcium chloride, the ether removed and the residue distilled, diphenyl diselenide and diphenyl selenide, B.pt. 303° C., being obtained. The sodium hydroxide solution on acidification with a slight excess of concentrated hydrochloric acid, followed by three more extractions with ether, gives on removal of the solvent almost pure phenyl selenide, B.pt. 182° C. The product melts at 60° C., and is insoluble in water, but dissolves in alcohol mercuric chloride gives a white precipitate.2... 

This work demonstrates a simple and rapid screening method for determination of methyl mercury in organic solvent using invertase inhibition. We have shown that this method is free from interferences using the solvent extraction combined with the invertase enzyme. 

Zhou, S., Zhou, H., Larson, M., Miller, D. L., Mao, D., Jiang, X., and Naidong, W. (2005). High-throughput biological sample analysis using on-line turbulent-flow extraction combined with monolithic column liquid chromatography/tandem mass spectrometry. Rapid Commun. Mass Spectrom. 19 2144-2150. 

Reprocessing is based on liquid-liquid extraction for the recovery of uranium and plutonium from used nuclear fuel (PUREX process). The spent fuel is first dissolved in nitric acid. After the dissolution step and the removal of fine insoluble solids, an organic solvent composed of 30% TriButyl Phosphate (TBP) in TetraPropylene Hydrogenated (TPH) or Isopar L is used to recover both uranium and plutonium the great majority of fission products remain in the aqueous nitric acid phase. Once separated from the fission products, back-extraction combined with a reduction of Pu(I V) to Pu(III) allows plutonium to be separated from uranium these two compounds can be recycled.2... 

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