Solvent partition method

Whitehead, J.K. and K. RothweU The mouse skin carcinogenicity of cigarette smoke condensate fractionated by solvent partition methods BriL J. Cancer 23 (1969) 840. 

Ladisch, S. and Gillard, B. (1985) A solvent partition method for microscale ganghoside purification. Anal. Biochem. 146, 220-231. 

An interesting consequence of selective sorption is that conditions for partition chromatography arise which may enhance the normal ion exchange separation factors. This aspect has been utilised by Korkisch34 for separation of inorganic ions by the so-called combined ion exchange-solvent extraction method (CISE). 

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)... 

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... 

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. 

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. 

The most common technique for the radiochemical determination of complexing constants utilizes partition methods which are based on reactions between two phases under static or dynamic conditions (chromatography). Partition methods offer the advantages of simplicity and rapidity and are amenable to a broad selection of phase compositions and arrangements. One of the most reliable partition methods, especially useful for measuring 0 , is solvent extraction. It is best applied to systems which exhibit compound formation (11). 

The fermentation broth typically contains 20-30 mg/L of antibiotics, which is to say 30 parts per billion, and must be extracted into concentrated form using solvent extraction. The solvent extraction method was developed by Shell Oil and by Podbielniack and is based on the principle that penicillin is hydrolyzed in aqueous medium to H+ and RCOO ions. Thus, equilibrium in an acidic medium (i.e., one with low pH or high H+ concentration) is favored by the neutral RCOOH form, whereas equilibrium in an alkaline medium (i.e., one with high pH or low H+ concentration) is favored by the RCOO ionic form. The neutral form is more soluble in an organic medium, and the ionic form is more soluble in an aqueous medium. Thus, with amyl acetate as the organic solvent the partition coefficient of penicillin between solvent and water is about 100 at pH 3 and about 1 at pH 6. In the industrial process, the aqueous broth was acidified to pH 3 for the extraction into the organic solvent, and alkalized to a pH 6 for reverse extraction back into an aqueous medium. 

The isolation method of solvent extraction has been suggested as a potentially feasible process to concentrate trace organic compounds from finished drinking water (4). One positive attribute of the solvent extraction method is that its performance for any given compound is theoretically predictable from a partition coefficient of a compound between the water sample and an organic solvent. The partition coefficient can be experimentally determined for any solute in any two-phase solvent system (7, 8). Variables of the extraction procedure such as solvent-to-water ratio and the choice of solvents can be adjusted to achieve optimum recovery. 

However, it is also fair to say that concerns about proliferation have been a problem, in that solvent-extraction methods have created the possibility to separate plutonium. Furthermore, nuclear researchers have to address several problems when developing partitioning processes, such as the use of flammable liquids, the disposal of spent solvents, as well as the fate of the chemicals introduced in the various parts of the processes to improve their performances (e.g., complexants and buffers added to the feeds or stripping solutions). 

Kawata et al. [ 128] have described the effects of headspace conditions on recoveries of volatile organic compounds from sediments and soils. Hewitt [129] compared three vapour partitioning headspace and three solvent extraction methods for the preparation of soil samples for volatile organic carbon determination in soils. Methanol extraction was the most efficient method of spiked volatile organic carbon recovery, which depended on the soil organic carbon content, the octanol-water partitioning coefficients of analytes and the extraction time. 

The International Union of Pure and Applied Chemistry (IUPAC) recommends the use of liquid-liquid distribution rather than the traditional term, solvent extraction. However, solvent extraction is still used commonly in the literature, and that is why it is also being used here interchangeably (Chapter 7). Solvent extraction utilizes the partition of a solute between two practically immiscible liquid phases—one a solvent phase and the other an aqueous phase. Liquid-liquid partitioning methods are important separation tools in modern biotechnology. They have become increasingly popular as part of a... 

The dimerization constants of carboxylic acids determined by the partition method are usually lower than the values obtained by IR spectroscopy, cryoscopy, or dielectric measurements (100). The correction for hydration gives dimerization constants expected from values in dry solvents by spectroscopic or dielectric measurements (29, 30). 

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