Extraction water-based

Dilute sodium hydroxide solution (and also sodium carbonate solution and sodium bicarbonate solution) can be employed for the removal of an organic acid from its solution in an organic solvent, or for the removal of acidic impurities present in a water-insoluble solid or liquid. The extraction is based upon the fact that the sodium salt of the acid is soluble in water or in dilute alkali, but is insoluble in the organic solvent. Similarly, a sparingly soluble phenol, e.g., p-naphthol, CioH,.OH, may be removed from its solution in an organic solvent by treatment with sodium hydroxide solution. 

Triturate 20 g. of dry o-toluidine hydrochloride and 35 5 g. of powdered iodine in a mortar and then grind in 17 -5 g. of precipitated calcium carbonate. Transfer the mixture to a conical flask, and add 100 ml. of distilled water with vigorous shaking of the flask. Allow the mixture to stand for 45 minutes with occasional agitation, then heat gradually to 60-70° for 5 minutes, and cool. Transfer the contents of the flask to a separatory funnel, extract the base with three 80 ml. portions of ether, diy the extract with anhydrous calcium chloride or magnesium sulphate, and remove the excess of solvent. The crude 5-iodo-2-aminotoluene separates in dark crystals. The yield is 32 g. Recrystallise from 50 per cent, alcohol nearly white crystals, m.p. 87°, are obtained. 

Until the 1980s, synthetic organic solvents commonly were used in the United States to extract the caffeine, either by direct contact as above or by an indirect secondary water-based system (36). In each case, steaming or stripping was used to remove residual solvent from the beans and the beans were dried to their original moisture content (10—12%) prior to roasting. 

Extraction from Aqueous Solutions Critical Fluid Technologies, Inc. has developed a continuous countercurrent extraction process based on a 0.5-oy 10-m column to extract residual organic solvents such as trichloroethylene, methylene chloride, benzene, and chloroform from industrial wastewater streams. Typical solvents include supercritical CO9 and near-critical propane. The economics of these processes are largely driven by the hydrophihcity of the product, which has a large influence on the distribution coefficient. For example, at 16°C, the partition coefficient between liquid CO9 and water is 0.4 for methanol, 1.8 for /i-butanol, and 31 for /i-heptanol. 

V. Janda, M. MikeSova and J. Vejrosta, Dkect supercritical fluid extraction of water-based mati ices , 7. Chromatogr. 733 35-40 (1996). 

C. Aguilar, I. Feirer, R Bonnll, R. M. Marce and D. Barcelo, Monitoring of pesticides in river water based on samples previously stored in polymeric cartridges followed by on-line solid-phase extraction-liquid cliromatography-diode array detection and confirmation by atmospheric pressure chemical ionization mass spectrometry . Anal. Chim. Acta 386 237-248 (1999). 

After the furfurel has all been added and the reaction has subsided, the residue is cooled, diluted with water, made strongly alkaline and distilled until all volatile substances are removed. The distillate is then made acid with formic acid and distilled with steam as long as nonbasic substances are carried over by the steam. The residue is then made strongly basic with caustic soda and the volatile amines again distilled with steem. The distillate is then treated with strong alkali and then extracted with ether to extract the base. The extract is dried by the addition of caustic potash, the ether removed and the residual amine purified by distillation. Furfuryl dimethyl amine boils over the range 145°C to 150°C. 

The major advantage of the use of two-phase catalysis is the easy separation of the catalyst and product phases. FFowever, the co-miscibility of the product and catalyst phases can be problematic. An example is given by the biphasic aqueous hydro-formylation of ethene to propanal. Firstly, the propanal formed contains water, which has to be removed by distillation. This is difficult, due to formation of azeotropic mixtures. Secondly, a significant proportion of the rhodium catalyst is extracted from the reactor with the products, which prevents its efficient recovery. Nevertheless, the reaction of ethene itself in the water-based Rh-TPPTS system is fast. It is the high solubility of water in the propanal that prevents the application of the aqueous biphasic process [5]. 

This method is relatively easy to use for anhydrous systems, but not for emulsions, foods, or biological media where the presence of water is detrimental. The method has been applied for determining antioxidant activity of both individual natural polyphenols and vegetable extracts. Methods based on this one have been used to evaluate the peroxide value in walnuts (Wilson-Kakashita and others 1995), mango seeds (Joseph 1995), almonds (Uthman and others 1998), and coconut cream powder (Yusof and others 2007). 

The iso-LSD salt can be converted back into the base by the addibon of methanolic KOH or potassium methoxide to the mother liquor. The resulting mixture should be added to a separatory funnel containing salt solution and ethylene dichloride. The LSD base is extracted into the ethylene dichloride layer (the lower layer). The lower layer is removed and fresh ethylene dichloride used to extract the last traces of LSD base from the salt water-base mixture. The ethylene dichloride extracts are combined, dried with MgSO, decolorized and filtered through diatomaceous earth as earlier. I he resulting ethylene dichloride solution may be combined with the chloroform solutions of iso-LSD which eluted from the chromatographic column. The combined solution may be evaporated to dryness under reduced pressure. 

Identification of compounds in the river water extracts was based on the coincidence of gas chromatographic retention times and on the equivalence of electron impact and chemical ionization mass spectra with those of authentic compounds. Quantitation was based on standard curves generated for selected compounds. 

Methods found for the determination of diazinon in animal products also used homogenization with a polar organic solvent as the first step in residue recovery. Toyoda et al. (1990) isolated diazinon from milk via partition into methylene chloride after extraction of the milk with 70% acetonitrile in water. Based on GC/FPD, an LOD of 10 ppb and a recovery of 89% (3.8% relative standard deviation) at 100 ppb were reported. Diazinon residues in eggs were studied (Leoni et al. 1992) after blending the eggs with acetone and partitioning into dichloromethane and acetone followed by C18-silica SPE. Based on GC/FPD analysis, an LOD of 1 ppb and a recovery of 93% at 13 ppb were reported. 

In this context, extraction means any process by which a fluid (air or water) comes into contact with a material to which the pollutant has an affinity. The affinity can be a physical trapping modified by some form of surface energy or a solvent extraction process based on enthalpic principles. The result is that the fluid is pumped through the sorption medium and the pollutant is reduced or eliminated from the fluid. Despite limitations, the most common sorption medium is activated charcoal — a form of charcoal treated with oxygen to open millions of tiny pores between the carbon atoms. It is amorphous and is characterized by high adsorptivity for many gases and vapors. 

The principle of extraction is based on a physical chemical phenomenon known as partitioning. If two fluids, one of which contains a solute that is soluble in both, come in contact with one another, the solute will migrate from the original fluid into the other fluid. The extent (but not the rate) to which it will migrate is governed by the relative solubilities of the fluids. See Table 4.2. If the solute is equally soluble in both fluids, half will continue to migrate until the concentrations in both fluids are the same. If the solute is much more soluble in one fluid or the other, the fluid in which the solute is most soluble will accumulate most of the solute. For instance, if ethanol is dissolved in water and contacted with a solvent, the amount of ethanol removed from the water depends on the solvent. 

Charged species tend to be more soluble in water than in organic solvent. To extract a base into water, use a pH low enough to convert B into BH+ (Figure 23-2). To extract the acid HA into water, use a pH high enough to convert HA into A-. 

A colorless or slightly yellow solid occurring in filamentous, granular, and powdered form. Forms a viscous cnlloidal solution with water, insoluble in alcohol, ether, and chloroform. It is extracted from brown seaweeds. The gum is used as a thickener, stabilizer, and emulsifier in foods, especially ice cream. Also used in boiler compounds, pharmaceuticals, textile printing, cement compositions, paper coatings, and in some water-base paints. 

Samples in — 55) fortified at different levels (4, 2, 1, and 0.5 mg/kg) were extracted and analyzed with the proposed electrochemical assay using both eeAChE and rAChE. For eeAChE, the recovery for di-chlorvos-spiked samples ranged between 74 and 78%. The incomplete recovery may be due to concurrent causes, such as the use of whole kernels as sample, water-based extraction solvent, and adsorption... 

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