Stability solid-liquid extraction

Stabilizers are identified after separation by solid-liquid extraction or after the removal of the polymer by precipitation from the diluted solution. Some extraction solvents for the most important stabilizers and polymers are given in Table 3. 

A close relationship between the resxxlts obtained by the Rancimat method was observed in the hydraxilic pressing and solid-liquid extractions. When the DSC time parameters were standardized, the results found for the oils extracted by hydraulic pressing showed a correlation between the oxidative stability methods applied of around 72%, with OSI values of 12.73 h for the Rancimat and 550 min for the DSC method. 

The oxidative stability values obtained by these methods of extraction using the Rancimat and DSC showed good correlation, indicating that both can be used as a parameter to assess the oxidative stability of oils, especially for the solid-liquid extraction with petroleum ether. 

The most common techniques utilised for the determination of the stability or solubility constants of metal hydroxide species and phases include ion exchange (solid-liquid extraction), distribution (liquid-liquid extraction), potentiometry, solubility and spectrophotometry. A brief outline of each of these techniques will be discussed. 

Krause, A.A. and Niemczyk, H.D. Gas-liquid chromatographic analysis of chlorthal-dimethyl herbicide and its degradates in turfgrass thatch and soil using a solid-phase extraction technique, J. Environ. Sci Health, B25(5) 587-606, 1990. Kresheck, G.C., Schneider, H., and Scheraga, H.A. The effect of DzO on the thermal stability of proteins. Thermod3mamic parameters for the transfer of model compounds from HzO to DzO, J. Phys. Chem., 69(9) 3132-3144, 1965. 

The submitters used du Pont 2-methylfuran. Since the stabilizer contained in this material inhibits the reaction, it should be removed before use. The liquid is stored over solid potassium hydroxide (10 g. for each 100 ml. of 2-methylfuran) for 24 hours, decanted, and stored over the same amount of fresh potassium hydroxide at least overnight. A more rapid but less convenient method of removing the stabilizer is to extract the liquid with 10% aqueous potassium hydroxide until the extracts are only faintly colored. 

The variations concern pH, temperature, time of processing, and, in the last case additionally, possible ultrasonic treatment. The following step consists in a liquid-phase or solid-phase extraction (SPE). However, other extraction methods like SFE ° also have been used prior to the detection procedure. The final choice of the workup procedure is mainly dependent on the chemical stability of the analyte e.g., benzodiazepines are highly unstable under alkaline conditions, but they are also affected under acid conditions. Alkaline hydrolysis should be avoided for cocaine - however, morphine can be extracted after acid or alkaline hydrolysis. ... 

Liquid-liquid extraction (LLE), solid phase extraction (SPE), and solid phase micro-extraction (SPME) are frequently applied for sample pretreatment. The type of extraction is highly related to the type of metabolites selected for determination. In previous metabolomics studies, extraction was focused on compounds of adequate stability that could be extracted together (carbohydrates, esters, amino acids, or organic acids). 

A spirothietane sulfone-oxetane is a comonomer in the preparation of polyethers. A polymer obtained from this sulfone in a solution of bis(3,3-chloromethyl) oxetane with phosphorus pentafluoride can be spun to drawable filaments. Thietane sulfone spirocyclic carbonates may be polymerized via the carbonate group to high-molecular-weight solids said to be useful in laminating. Thietane 1,1-dioxide improves the dye receptivity of poly (acrylonitrile), viscose, cellulose acetate, and poly(vinyl chloride). It is also reported to be a stabilizer for nitric acid in oxidizer mixtures for rocket motors. 2-Methylthietane 1,1-dioxide is claimed to be superior to sulfolane (thiolane 1,1-dioxide) in the liquid extraction of aromatic hydrocarbons from mixtures with saturated hydrocarbons. " A number of bis(3,3-alkoxy) thietane 1,1-dioxides have been proposed as intermediates in the preparation of cyanine dyes useful as photographic sensitizers. " ... 

PL membranes are usually cast from a homogeneous solution of the dissolved solid polymer material (e.g., poly(vinyl chloride)), the liquid extractant (e.g., Aliquat 336 chloride DEHPA) and a plasticizer (e.g., dioctylphtalate n-decanol) in a suitable solvent (e.g., tetrahydrofuran) by the slow evaporation of the solvent. By increasing the concentration of the extractant the permeability of the PL membrane increases while at the same time its mechanical stability deteriorates. For example, the optimal concentration range for Aliquat 336 chloride in a polyvinyl chloride based PL membrane is between 40 and 50%. 

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