Extracting solution

Formaldehyde from cigarette smoke is collected by trapping the smoke in a 1-L separatory funnel and extracting into an aqueous solution. To aid in its detection, cysteamine is included in the aqueous extracting solution, leading to the formation of a thiazolidine derivative. Samples are analyzed... 

From Example A6.2 we know that after 100 steps of the countercurrent extraction, solute A is normally distributed about tube 90 with a standard deviation of 3. To determine the fraction of solute in tubes 85-99, we use the single-sided normal distribution in Appendix lA to determine the fraction of solute in tubes 0-84 and in tube 100. The fraction of solute A in tube 100 is determined by calculating the deviation z (see Chapter 4)... 

The physical process of Hquid—Hquid extraction separates a dissolved component from its solvent by transfer to a second solvent, immiscible with the first but having a higher affinity for the transferred component. The latter is sometimes called the consolute component. Liquid—Hquid extraction can purify a consolute component with respect to dissolved components which are not soluble in the second solvent, and often the extract solution contains a higher concentration of the consolute component than the initial solution. In the process of fractional extraction, two or more consolute components can be extracted and also separated if these have different distribution ratios between the two solvents. 

The development of the novel Davy-McKee combined mixer—settler (CMS) has been described (121). It consists of a single vessel (Fig. 13d) in which three 2ones coexist under operating conditions. A detailed description of units used for uranium recovery has been reported (122), and the units have also been studied at the laboratory scale (123). AppHcation of the Davy combined mixer electrostatically assisted settler (CMAS) to copper stripping from an organic solvent extraction solution has been reported (124). 

As metal extraction into a diluent—extractant solution proceeds, there is sometimes a tendency for formation of two organic phases in equiHbrium with the aqueous phase. A third phase is highly undesirable and its formation can be prevented by adding to the organic phase a few percent of a modifier which is typically a higher alcohol or tri- -butyl phosphate (TBP) (7). 

The distribution of highly extractable solutes such as and Pu between the aqueous and organic phases is strongly dependent upon the nitrate anion concentration in the aqueous phase. This salting effect permits extraction or reextraction (stripping) of the solute by controlling the nitric acid concentration in the aqueous phase. The distribution coefficient, D, of the solute is expressed as... 

Mechanism The mechanism of leaching may involve simple physical solution or dissolution made possible by chemical reaction. The rate of transport of solvent into the mass to be leached, or of soluble fraction into the solvent, or of extract solution out of the insoluble material, or some combination of these rates may be significant. A membranous resistance may be involved. A chemical-reaction rate may also affec t the rate of leaching. 

More recently, a modification of the system described by Kreibich has been used extensively in industry with good success. Part A of the adhesive is again a standard phenol-resorcinol-formaldehyde (PRF) cold-setting adhesive, with powder hardener added at its standard pH. Part B can be either the same PRF adhesive with no hardener and the pH adjusted to 12, or a 50 to 55% tannin extract solution at a pH of 12-13, provided that the tannin is of the condensed or flavonoid type, such as mimosa, quebracho, or pine bark extract, with no hardener [118,135-137], The results obtained with these two systems are good and the resin not only has all the advantages desired but also the use of vegetable tannins and the halving of the resorcinol content makes the system considerably cheaper [118,135-137]. 

Tannins are polyhydroxyphenols. They are soluble in water, aleohols and aeetone and ean eoagulate proteins. They are yielded by extraetion from wood substanee, bark, leaves and fruits. Other components of the extraction solutions are sugars, pectins and other polymeric carbohydrates, amino acids and other substances. The content of non-tannins can reduce wood failure and water resistance of glued bonds. The polymeric carbohydrates especially increase the viscosity of the extracts. 

Lube oil extraction plants often use phenol as solvent. Phenol is used because of its solvent power with a wide range of feed stocks and its ease of recovery. Phenol preferentially dissolves aromatic-type hydrocarbons from the feed stock and improves its oxidation stability and to some extent its color. Phenol extraction can be used over the entire viscosity range of lube distillates and deasphalted oils. The phenol solvent extraction separation is primarily by molecular type or composition. In order to accomplish a separation by solvent extraction, it is necessary that two liquid phases be present. In phenol solvent extraction of lubricating oils these two phases are an oil-rich phase and a phenol-rich phase. Tne oil-rich phase or raffinate solution consists of the "treated" oil from which undesirable naphthenic and aromatic components have been removed plus some dissolved phenol. The phenol-rich phase or extract solution consists mainly of the bulk of the phenol plus the undesirable components removed from the oil feed. The oil materials remaining... 

Stripping. Stripping is the removal of the extracted solute from the organic phase for further preparation for the detailed analysis. In many analytical procedures involving an extraction process, however, the concentration of the desired solute is determined directly in the organic phase. 

Figure 5.60 Calibration curves for the diarrhetic shellfish poisons in (i) standard solutions in methanol (O), and (11) standard solutions in poison-free scallop extract solutions ( ) (a) pectenotoxin-6 (b) okadaic acid (c) yessotoxin (d) dinophysistoxin-1. Reprinted from J. Chromatogr., A, 943, Matrix effect and correction by standard addition in quantitative liquid chromatographic-mass spectrometric analysis of diarrhetic shellfish poisoning toxins , Ito, S. and Tsukada, K., 39-46, Copyright (2002), with permission from Elsevier Science.

Figure 11.17a to Figure 11.17d show densitograms from the separation of Che-lidonium majus quaternary alkaloids. Various volumes of the extract solution of the same concentration, from 0.2 to 1.6 ml, were introduced to the adsorbent layer. Thus, the following portions of extract of 0.25, 0.5, 1, and 2 mg were chromatographed by the use of threefold development with the multicomponent eluent. The densitograms depict fast loss of resolution with the increase of the introduced sample [114]. 

Fortifications are made by pipetting 100-500 o.L of the appropriate standards in acetonitrile on to the sample (10 g) before any extraction solution is added and then allowing the sample to air dry for 30 min. 

Add 20 mL of MeOH-30mM NaOAc solution (4 1, v/v NaOAc adjusted to pH 2.5-3) to the soil, and then the mixture should be vortex mixed for 30 s, sonicated for 5 min, vortex mixed momentarily, and centrifuged for 5 min at 2500 rpm. Decant the supernatant into a clean lOO-mL graduated cylinder. Repeat the first two steps twice for a total of 60 mL of extraction solution used (dilute to 60 mL with MeOH as necessary). Transfer the solution into a glass, capped bottle (pour back and forth twice to mix). 

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