Ratios extractants

Extraction temperature Mass extract Mass THF Ratio extract/THF Mass cake Filtrate - mass - ash... 

Optimization of the MAE procedure consists in choosing an appropriate solvent (or solvent mixture) and others factors such as solvent-to-feed ratio, extraction time and temperature, microwave power, and matrix characteristics (including water content). 

Drug Substrate for Efflux ratio Extraction ratio (%) SD ... 

Despite recent efforts toward settling operational conditions for metal and metalloid fractionation assays—in terms of concentration, pH, and temperature for each of the leaching reagents, sample weight/extractant volume ratio, extraction time, shaking protocol, analytical instrumentation, and phase separation method —conventional sequential extraction schemes lack automation and are inherently rather time consuming and laborious. This is the consequence of a number of steps needed for the separation, identification, and quantification of TEs in each fraction. For example, the SM T recommended protocol lasts more than 50 hours, whereas the operating time of Tessier s scheme approaches 20 hours. 

It is acknowledged that the interference of the C-C peak of PAni and the G band may have a small effect on the analysis of the intensity of the G band for measurement of the degree of orientation of SWNTs and the distribution function. The intensity ratio data (ly (v /°) / lyy (v / = 0°)) versus v / for composite fibers are represented in Figure 7, for G and RBM bands. A small difference in intensity ratio at each / was observed for the G and RBM bands in the drawn PAni-ES/AMPSA-SWNTefibers. However, a comparison of data obtained for G band and RBM intensity ratios extracted from references [48,50] and for SWNT fibers exhibit a similar discrepancy. It can, therefore, be assumed that the interference between the PAni C-C peak and the G band has little effect on the intensity ratio. It can be seen from Figure 7 that the intensity ratio obtained in the present work is similar to previously published data [50,57]. 

Pasquini et al. reported that cellulose whiskers with high aspect ratio extracted directly from cassava bagasse were used to prepare NR nanocomposite films by mixing with the NR latex emulsion. The mixtures were cast on Teflon plates and dried overnight to obtain composite films. These NR nanocomposite films were not vulcanized by standard process. They found that a significant increase of the storage tensile modulus was observed upon filler addition by dynamic mechanical analysis. 

Fi fure 6. Dependence of the amount of extract on solvent ratio. Extraction of caffeine from raw coffee beans with supercritical nitrous oxide (N2O) [2]. 

Cobalt Distribution Ratio. Extraction Rate and Optimum Extraction pH Value... 

The distribution ratio, extraction rate and extraction volume, optimum extraction pH were determined, cobalt and nickel elution curves were obtained and the process conditions for chromatographic separation were defined. 

Crude and extracts. Crude and syrup were formerly official in U.S.P., and fluid extract was official in N.F. The crude comes in two types thin and thick with the former being considered superior in quality. Strengths (see glossary) of extracts are expressed in weight-to-weight ratios extracts may contain detectable amounts of prunasin or its hydrolysis product, HCN. 

Table 15.4 Acid/base ratios of the van Oss-Good parameters (+/-) from various sources as compared to the acid/ base ratios extracted from Kamlet-Taft parameters a/p (original values and normalized values from Lee)...

Next to last iterative value of extract-feed ratio. 

Change in extract-feed ratio from one iteration to the next. Partial derivative of Rachford-Rice objective function with respect to extract-feed ratio. 

DI Fractional change in extract-feed ratio during last two iterations. 

KS Temporary storage of equilibrium ratio for extract solvent. 

The geometrical measurements previously extracted help the making decision system to decide for example whether the defect is linear or not. This defect discrimination into two categories is considered as a first attempt for defect classification. To this end, we define a linearity ratio (Ri) Rl =Length / width. If Rl is equal or near to "1", the defect is volumic, otherwise it is a linear defect. 

The theory of the process can best be illustrated by considering the operation, frequently carried out in the laboratory, of extracting an orgaiuc compound from its aqueous solution with an immiscible solvent. We are concerned here with the distribution law or partition law which, states that if to a system of two liquid layers, made up of two immiscible or slightly miscible components, is added a quantity of a third substance soluble in both layers, then the substance distributes itself between the two layers so that the ratio of the concentration in one solvent to the concentration in the second solvent remains constant at constant temperature. It is assumed that the molecular state of the substance is the same in both solvents. If and Cg are the concentrations in the layers A and B, then, at constant temperature ... 

The constant K is termed the distribution or partition coefficient. As a very rough approximation the distribution coefficient may be assumed equal to the ratio of the solubilities in the two solvents. Organic compounds are usually relatively more soluble in organic solvents than in water, hence they may be extracted from aqueous solutions. If electrolytes, e.g., sodium chloride, are added to the aqueous solution, the solubility of the organic substance is lowered, i.e., it will be salted out this will assist the extraction of the organic compound. 

In a typical experiment 105 mg (0.50 mmol) of 3.8c, dissolved in a minimal amount of ethanol, and 100 mg (1.50 mmol) of 3.9 were added to a solution of 1.21g (5 mmol) of Cu(N03)2 BH20 and 5 mmol of ligand in 500 ml of water in a 500 ml flask. -Amino-acid containing solutions required addition of one equivalent of sodium hydroxide. When necessary, the pH was adjusted to a value of 5 ( -amino acids) and 7.5 (amines). The flask was sealed carefully and the solution was stirred for 2A hours, followed by extraction with ether. After drying over sodium sulfate the ether was evaporated. Tire endo-exo ratios were determined from the H-NMR spectra of the product mixtures as described in Chapter 2. 

Endo-exo ratios of the micelle-catalysed reactions have been determined by adding 0.25 mmol of 5.1c and 0.5 mmol of 5.2 to a solution of 5 mmol of surfactant and 0.005 mmol of EDTA in 50 ml of water in carefully sealed 50 ml flasks. The solutions were stirred for 7 days at 26 C and subsequently freeze-dried. The SDS and CTAB containing reaction mixtures were stirred with 100 ml of ether. Filtration and evaporation of the ether afforded the crude product mixtures. Extraction of the Diels-Alder adducts from the freeze-dried reaction mixture containing C12E7 was performed by stirring with 50 ml of pentane. Cooling the solution to -18 C resulted in precipitation of the surfactant. Filtration and evaporation of the solvent afforded the adduct mixture. Endo-exo ratios... 

Extraction Between Two Phases When the sample is initially present in one of the phases, the separation is known as an extraction. In a simple extraction the sample is extracted one or more times with portions of the second phase. Simple extractions are particularly useful for separations in which only one component has a favorable distribution ratio. Several important separation techniques are based on simple extractions, including liquid-liquid, liquid-solid, solid-liquid, and gas-solid extractions. 

In evaluating the efficiency of an extraction, however, we must consider the solute s total concentration in each phase. We define the distribution ratio, D, to be the ratio of the solute s total concentration in each phase. 

In the simplest form of liquid-liquid extraction, the only reaction affecting extraction efficiency, is the partitioning of the solute between the two phases (Figure 7.20). In this case the distribution ratio and the partition coefficient are equal. 

For a simple liquid-liquid extraction, the distribution ratio, D, and the partition coefficient, Kd, are identical. 

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