Organic compounds filter, solvent extraction

Organic solvent extraction. Two analytical methods for acetamiprid have been developed One method is for the parent only and the other determines the total residue of the parent and its metabolites (lM-1-2, lM-1-4 and lC-0). Air-dried soil (20-g equivalent dry soil) is weighed into a centrifuge tube and imidacloprid residue is extracted with 100 mL of methanol-0.1M ammonium chloride (4 1, v/v) using a mechanical shaker for about 30 min. After shaking, the tube is centrifuged at 8000 rpm for 2 min. The supernatant is filtered and the analysis of the soil residue is carried out in the same manner as described above for the parent compound. 

In both results of solubility and desorption from filter papers, diethylamine in methanol as a modifier was found to offer greater efficiency for SFE of the alkaloids than any other modifiers employed. The yields of hyoscyamine (1) and scopolamine (2) from the roots and aerial parts by SFE and conventional organic solvent extraction are listed in Tables 2 and 3. The SFE yields from both plant parts were greatly enhanced by the addition of methanol basified with diethylamine. From the results of solubility and desorption from filter paper, methanol and diethylamine/methanol (10% v/v) were much more efficient for both compounds than water and diethylamine/water (10% v/v) because of their low miscibility with C02. The extraction profile of hyoscyamine (1) when present in plant material was in good agreement with that when extracted as a pure compound. However, in the case of scopolamine (2), there... 

The organic fraction present in atmospheric particles is a highly complex mixture, which makes the speciation of individual compounds a difficult task. The traditional analytical approach has usually been solvent extraction of aerosol particles collected in a filter followed by gas chromatographic separation coupled to mass spectrometry (GC-MS) detection for individual compound identification and quantification. Although a large number of compounds, sometimes in trace amounts, have been... 

Lipopholic products are usually separated by extraction of the filtered broth, or the whole culture including the biomass, with water immiscible organic solvents, followed by separation of the solvent extracts and concentration in a vacuum evaporator. Chloroform, dichloromethane and ethyl acetate have been widely used as extraction solvents, however, 4-methyl-2-pentanone (methyl isobutyl ketone) appears to be the solvent of choice in the case of steroid substrates. Hydrophilic products, which cannot be extracted by organic solvents, can be isolated by ion exchange or by selective adsorption to polymeric resins (e.g., Amberlite XAD-resins). Resins of a wide range of polarity are available and lipophilic compounds can also be separated by this method. Final purification is accomplished in the usual way by crystallization, distillation or column chromatography. Preparative HPLC is a powerful tool for purification of small product quantities. 

Extraction discs are suitable only for clean water samples. The organic compounds are removed from the water as it is filtered through the extracting disc and then the compounds are eluted with a suitable solvent. 

The procedures used by different laboratories to extract, isolate, and analyze the biomarker hydrocarbon contents of sediments are rarely identical, but they differ largely only in their details. The general analytical scheme in which the fundamental elements common to the different procedures has been nicely summarized by Rullkotter (2000). For their analysis, hydrocarbons first need to be separated from sediments by extraction into an organic solvent. The most common solvent that is used for dried sediment samples is dichloromethane, although other solvents or mixtures of solvents are also employed. A risk involved with the common practice of first drying the sediments is that some organic compounds may become irreversibly associated with minerals and will not be released by subsequent solvent extraction. Moreover, freeze-drying of sediment samples can sometimes create a more serious problem — contamination of the natural hydrocarbon composition with pump oil vapors (Barwise et al., 1996) — unless suitable filters are employed. For these reasons, extraction of wet sediment samples is sometimes preferred. In these cases, solvents like methanol or acetone that can remove the sediment porewater are used first and then followed by mixtures of these hydrophilic solvents with non-polar solvents such as dichloromethane. 

SCE-based processes such as GAS process, SAS process, aerosol solvent extraction system (ASES), SEDS address low solubility of the compounds in SCCO2. In these processes, the drug, polymer, or both are dissolved in an organic solvent to form a solution. Solvents used may include dimethyl sulfoxide, N-methyl pyrrolidone, methanol, ethanol, acetone, chloroform, or isopropanol. To successfully produce ASD, the drug and polymer should exhibit limited solubility in SCF and the organic solvent should be miscible with carbon dioxide. Collection of the precipitated particles in the antisolvent is carried out in the same vessel where solvent extraction takes place. The particles are collected on a filter unit located at the bottom of the vessel. 

The reduction is effected exactly as in Procedure 8a but using 0.61 g (0.088 g-atom) of lithium. After the crude reaction product has been washed well on the filter with cold water, it is dissolved in ethyl acetate, the solution is filtered through the sintered glass funnel to remove iron compounds from the ammonia, and the filtrate is extracted with saturated salt solution. The organic layer is dried over sodium sulfate and the solvent is removed. The solid residue is crystallized from methanol (120 ml) using Darco. The mixture is cooled in an ice-bath, the solid is collected, rinsed with cold methanol, and then air-dried to give 12.9 g (85%), mp 129-132° reported for the tetrahydropyranyi ether of 3j5-hydroxypregn-5-en-20-one, mp 129-131°. 

The aqueous fraction was acidified to pH 1 with 6N HC1, and the small amount of humic acids which precipitated was removed by filtration. The filtrate was extracted three times with 100-ml portions of ethyl acetate. The organic extracts were combined, dried over anhydrous sodium sulfate, and filtered. The solvent was removed by rotary evaporation and the residue contained the freed byproducts from the hydrolyzed esterified and insoluble-bound compounds. 

While most of the interest in sterols has been in the materials in solution, Kanazawa and Teshima [417] have investigated the compounds present in suspension. The suspended matter was fractionated by filtration through a graded series of filters, the sterols removed by extraction with an organic solvent, and the final separation and determination was made by flame ionisation gas chromatography. 

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