Partitioning solvent

Fatty foods (>2% fat) Extraction of fat using sodium sulfate, petroleum ether, by filtering, or by solvents oleanup using solvent partitioning, Florisil GC/ECD No data >85% ( r T sulfate) FDA 1994 (PAM Method 304)... 

Processes based on fluidized bed coating have been developed (49). In this process, the bioactive agent is dissolved in an organic solvent along with the polymer. This solution is then processed through a Wurster air suspension coater apparatus to form the final microcapsule product. A solvent partition technique based on continuous injection of a polymer-drug solution into flowing mineral oil has been reported (50). 

COPLAND E L, CLIFFORD M N and WILLIAMS c M (1998) Preparation of (-)-epigallocatechin gallate from commercial green tea by caffeine precipitation and solvent partition . Food Chem, 61, 81-7. 

Internal Standards. A compound selected as an internal standard ideally should behave in a manner identical to that of the analyte in all separation steps in the analytical process and should be measured by the same final determination method. Distillation from aqueous systems and solvent partition are the... 

Thousands of polyphenols from fruits (grapes, apples, etc.), vegetables (horse beans), and teas have been identified, many having good coloring properties, especially anthocyanins and some flavonoids. Well-documented reviews discuss the coloring capacities of some polyphenols including procyanidins. - Detailed presentations of anthocyanin and flavonoid properties and analysis are included in Sections 2.3, 4.3, and 6.3. The soluble proanthocyanidins of the colored horse bean Viciafaba L. seed coats were isolated and separated by solvent partition. 

AM columns are another means of measuring lipophilic characteristics of drug candidates and other chemicals [99-103]. 1AM columns may better mimic membrane interactions than the isotropic octanol-water or other solvent-solvent partitioning system. These chromatographic indices appear to be a significant predictor of passive absorption through the rat intestine [128]. 

For multi-analyte and/or multi-matrix methods, it is not possible to validate a method for all combinations of analyte, concentration and type of sample matrix that may be encountered in subsequent use of the method. On the other hand, the standards EN1528 andEN 12393 consist of a range of old multi-residue methods. The working principles of these methods are accepted not only in Europe, but all over the world. Most often these methods are based on extractions with acetone, acetonitrile, ethyl acetate or n-hexane. Subsequent cleanup steps are based on solvent partition steps and size exclusion or adsorption chromatography on Florisil, silica gel or alumina. Each solvent and each cleanup step has been successfully applied to hundreds of pesticides and tested in countless method validation studies. The selectivity and sensitivity of GC combined with electron capture, nitrogen-phosphorus, flame photometric or mass spectrometric detectors for a large number of pesticides are acceptable. 

Pyridine and BF3 in methanol are hazardous and must be used only in a well-ventilated hood. A solvent partition after acylation helps remove residual pyridine from the sample. Material Safety Data Sheets for the derivatizing agents should be reviewed and kept readily available. 

The adjustment of the pH in the step Hexane Solvent Partitions to pH 7 should be... 

Residues are extracted with acetone. The extract is rotary evaporated to remove acetone, the concentrated residue is diluted with 5% aqueous sodium chloride, and residues are partitioned into dichloromethane. The extract is then concentrated and purified on a silica gel column. Residues of pyriproxyfen are quantitated by gas chromatography with nitrogen-phosphorus detection (GC/NPD). For citrus, a hexane-acetonitrile solvent partition step is required for oil removal prior to the dichloromethane partition step. 

The effect of biphasic mixtures on the productivity includes the contributions of solvent partitioning on enzyme activity and stability. An important activity does not necessarily lead to increased productivity. We must then distinguish between the effect of the environment on activity and productivity. 

Figure 8.9 Solvent partition schene for the isolation of polychlorinated biphenyls from fat samples.

Figure 8.12 Selective solvent partition scheae for isolating polar auid unsaturated solutes.

Decaffeination of green coffee beans is most usually carried out with a water/solvent partition system. The green coffee beans are first steamed until they are hot, wet, and swollen, to make the caffeine available. Solvent is then used to extract the caffeine out of the aqueous phase of the beans. Finally, the beans are steamed to drive off residual solvent. The coffee beans lose their wax surface covering in the process, as well as some flavor components. For this reason, the Robusta and Brazilian Arabica coffees that are dry-processed and have the most powerful flavors are usually the types that are decaffeinated. They become milder in the process. Mechanical polishing is used to improve the appearance of decaffeinated green coffee beans if they are not to be roasted immediately. Extra care is required, however, to store these decaffeinated beans since the loss of wax covering as well as caffeine renders them much more susceptible to fungal attack. 

For the analysis of organic additives in polymeric materials, in most cases, prior extraction will be necessary. Depending on the nature of the additive, many different approaches are employed. These include soxhlet extraction with organic solvent or aqueous media, total sample dissolution followed by selective precipitation of the polymer leaving the additive in solution, assisted extraction using pressurised systems, ultrasonic agitation and the use of supercritical fluids. In trace analysis, solid phase extraction (SPME) from solution or solvent partition may be required to increase the analyte concentration. 

Cruz, A., Fernandes, P., Cabral, J.M.S. and Pinheiro, H.M. (2004) Solvent partitioning and whole-cell sitosterol bioconversion activity in aqueous-organic two-phase systems. Enzyme and Microbial Technology, 34, 342-353. 

A sensitive method was described for the detection and estimation of residues of niclosamide in bananas involving extraction of niclosamide, purification of the extract by solvent partition and column chromatography, formation of the hepta-fluorobutyryl derivative of 2-chloro-4-nitroaniline in 99% yield, and determination of the derivative by gas liquid chromatography with electron capture detection. 

Solvent-partitioned mixtures are fractionated further by column chromatography involving Sephadex LH-20, silica gel, or a combination [19]. Quantitative recovery of constituents is often possible with Sephadex chromatography. With a MeOH/CHCl3 (1 1) eluent, pigmented and other polar material is removed in the early fractions, while the nonpolar isonitrile-related compounds elute later. 

Jenke, D.R., Hayward, D.S., Kenley, R.A. (1990) Liquid chromatographic measurement of solute/solvent partition coefficients application to solute/container interactions. J. Chromatogr. Sci. 20, 609-6612. 

Shinohara et al. [299] have described a procedure based on gas chromatography for the determination of traces of two, three, and five-ring azarenes in seawater. The procedure is based on the concentration of the compounds on Amberlite XAD-2 resin, separation by solvent partition [300], and determination by gas chromatography-mass spectrometry with a selective ion monitor. Detection limits by the flame thermionic detector were 0.5-3.0 ng and those by gas chromatography-mass spectrometry were in the range 0.02-0.5 ng. The preferred solvent for elution from the resin was dichloromethane and the recoveries were mainly in the range 89-94%. 

Tan [71] devised a rapid simple sample preparation technique for analysing polyaromatic hydrocarbons in sediments. Polyaromatic hydrocarbons are removed from the sediment by ultrasonic extraction and isolated by solvent partition and silica gel column chromatography. The sulphur removal step is combined into the ultrasonic extraction procedure. Identification of polyaromatic hydrocarbon is carried by gas chromatography alone and in conjunction with mass spectrometry. Quantitative determination is achieved by addition of known amounts of standard compounds using flame ionization and multiple ion detectors. 

Effects of different fractions obtained from LC after solvent partition of the crude extract on capillary permeability induced by acetic acid in mice are shown in Tables 8.1 and 8.2. 

Organic solvents Partition coefficients Miscible with alcohol, ether Windholz1983... 

Zhang, L., Rafferty, J.L., Siepmann, J.I., Chen, B., and Schure, M.R., Chain conformation and solvent partitioning in reversed-phase liquid chromatography Monte Carlo simulations for various water/methanol concentrations, J. Chromatogr. A, 1126, 219, 2006. 

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