Extraction dichloromethane-methanol

The most critical decision to be made is the choice of the best solvent to facilitate extraction of the drug residue while minimizing interference. A review of available solubility, logP, and pK /pKb data for the marker residue can become an important first step in the selection of the best extraction solvents to try. A selected list of solvents from the literature methods include individual solvents (n-hexane, " dichloromethane, ethyl acetate, acetone, acetonitrile, methanol, and water ) mixtures of solvents (dichloromethane-methanol-acetic acid, isooctane-ethyl acetate, methanol-water, and acetonitrile-water ), and aqueous buffer solutions (phosphate and sodium sulfate ). Hexane is a very nonpolar solvent and could be chosen as an extraction solvent if the analyte is also very nonpolar. For example, Serrano et al used n-hexane to extract the very nonpolar polychlorinated biphenyls (PCBs) from fat, liver, and kidney of whale. One advantage of using n-hexane as an extraction solvent for fat tissue is that the fat itself will be completely dissolved, but this will necessitate an additional cleanup step to remove the substantial fat matrix. The choice of chlorinated hydrocarbons such as methylene chloride, chloroform, and carbon tetrachloride should be avoided owing to safety and environmental concerns with these solvents. Diethyl ether and ethyl acetate are other relatively nonpolar solvents that are appropriate for extraction of nonpolar analytes. Diethyl ether or ethyl acetate may also be combined with hexane (or other hydrocarbon solvent) to create an extraction solvent that has a polarity intermediate between the two solvents. For example, Gerhardt et a/. used a combination of isooctane and ethyl acetate for the extraction of several ionophores from various animal tissues. 

Residues are extracted with methanol-0.1 M sodium hydroxide (NaOH) (4 1, v/v). The extract is rotary evaporated to remove the methanol, the concentrated residue is diluted with water (at neutral pH), and the residues are partitioned into dichloromethane. The extract is purified using an alumina column. Pyriproxyfen residues are quantitated by GC/NPD. 

A specific assay of bromocriptine mesilate in the dosage form may be carried out by tic followed by uv-spectrophotometry (26)(The system can also serve for identification purposes). The drug substance is extracted with methanol in the absence of light, the chromatographic conditions are Merck plates F 254, mobile phase dichloromethane/dioxane/ ethanol abs./conc. ammonia 180 15 5 0.1 per volume. 

DHDMABb, BDMHAC0 NPEOl + 2, Sludge-amended soil extraction (all methanol) Soxhlet (dichloromethane) derivatisation (cationics) (LAS, NPEO) NP-HPLC-FL (cationics) NP-HPLC-FL 0.07-1.21 [25]... 

Isolation of curcumin from turmeric has been obtained by TLC. It has been reported that curcumin [(E,E)-l,7-bis(4-hydroxy-3-methoxyphenyl)-l,6-heptadiene-3,5-one] may have antitumour and anticancer activities. Turmeric was ground and a sample of 20g was refluxed with 50 ml of dichloromethane for 1 h. The suspension was filtered and concentrated at 50°C. The residue was triturated with 20 ml of n-hexane. The rest was analysed by TLC using a silica stationary phase and dichloromethane-methanol (97 3, v/v) as the mobile phase. It was found that TLC separated the crude extract in three fractions with RP values of 0.49, 0.22, and 0.085 [310],... 

For a recovery of (S)-a,a-diphenylprolinol, which is the hydrolysis product of the CBS-catalyst (S)-5 (and likewise its synthetic precursor ), the aqueous phase is carefully adjusted to pH 10 with concentrated ammonia and extracted with diethyl ether (3 x 50 ml). The combined organic layers are washed with brine (50 mL) and dried over MgS04. Removal of the solvent by rotary evaporation yields 1.68 g (79%) of crude (S)-a,a-diphenylprolinol. This material is dissolved in dichloromethane / methanol 9 1 (3 ml) and filtered over Alox B (act. Ill, 80 g) with dichloromethane / methanol 9 1 as the eluent, to yield 1.64 g (77%) of (S)-a,a-diphenylprolinol as a white solid. 

Carotenoids A large number of solvents have been used for extraction of carotenoids from vegetables matrices, such as acetone, tetrahydrofuran, n-hexane, pentane, ethanol, methanol, chloroform [427-431], or solvent mixtures such as dichloromethane/methanol, tetrahydrofuran/methanol, -hexane/acetone, or toluene or ethyl acetate [424,432-435], SPE has been used as an additional purification step by some authors [422,426], Supercritical fluid extraction (SEE) has been widely used, as an alternative method, also adding CO2 modifiers (such as methanol, ethanol, -hexane, water, methylene chloride) to increase extraction efficiency [436-438], In addition, saponification can be carried out, but a loss of the total carotenoid content has been observed and, furthermore, direct solvent extraction has been proved to be a valid alternative [439],... 

The purification of bacterial constituents usually starts in a very conventional way with an extraction step of the crude broth at neutral or slightly acidic pH. Mycelium-forming organisms are separated by filtration, and the cell mass and the filtrate are extracted separately. For the liquid phase, adsorber resins allow high recovery rates of metabolites and low process costs due to repeated use of the resins. If liquid-liquid extraction has to be applied, medium or highly polar solvents are favored. Ethyl acetate is the solvent of choice, and only in few cases is butanol superior. To extract the moist cell material, ethyl acetate, acetone or dichloromethane/methanol can be used. 

The complexes were prepared from [CODRhCl]2 and 1.1 equiv of chiral diphosphine in dichloromethane as solvent. The chiral complex was added to a suspension of the support in dichloromethane. After being stirred for 24 h, the solid was filtered, washed with dichloromethane until the solvent showed no color, and afterward dried at room temperature for 16 h. In order to remove the excess of Rh complex not fixed to the solid carrier, the catalysts were extracted with methanol in a Soxhlet apparatus under reflux for 24h (Scheme 2.1.6.1). Both ICP-AES analysis and FTIR spectra of the remaining solvent indicated no content of homogeneous complex. The resulting catalysts had a pale yellow color similar to that of the homogeneous complex. 

A special case is the test of immobilization of rhodium-diphosphine complexes on all-silica materials. After the first immobilization step in dichloromethane, the solid material had a yellow color and a Rh content of 0.07 mmol g was found. After the extraction with methanol, the entire amount of organometallic complex was washed out and the final material had again the original white color. No rhodium was detected in ICP-AES analysis of this sample. However, in the case of aluminum-containing materials the orange color obtained after the immobilization of the rhodium complexes in dichloromethane is clearly maintained even after extraction in methanol. 

Fruit, vegetables Homogenized with acetone, extraction dichloromethane-petroleum eter, centrifuged Shodex DE-613 (150 X 6.0 mm, 6 yum) phosphate buffer-methanol (30 70), pH 7.0 Fluorimetric, ex. 235 nm, em. 280 nm 50... 

Fig. 10 Curves of capacity obtained after the percolation of (1) 5 mL, (2) 10 mL, and (3) 25 mL of a dichloromethane-methanol (99 1) mixture spiked with increasing amount of atrazine on the terbutylazine MIP (130 mg). The dotted line corresponds to a slope of 1 meaning an extraction recovery of 100% [48]...

The samples were ground and extracted with the solvent mixture 9 1 dichloromethane/methanol for 48 hours in a soxhlet system. The extracted samples were then demineralized to isolate kerogens using a detailed procedure described in (3). Hie kerogen was next solvent extracted a second time and treated with 0.2 N nitric acid at room temperature to separate pyrite from the organic matter and the solution was kept for determination of pyrite S content and isotopic composition. X-ray diffraction was used to verify the removal of pyrite from the kerogen. 

General Procedures. Optical brightness pads of hardwood BCTMP and cellulose were prepared following TAPPI procedures (IS). All handsheets were extracted with methanol followed by dichloromethane, vacuum dried, and stored at below 0° C prior to use. Cotton linter handsheets had an average Tappi brightness value of 86.5 0.1 and the BCTMP... 

A study compared ASE and SFE to Soxhlet and sonication in the determination of long-chain trialkylamines (TAMs) in marine sediments and primary sewage sludge [89], The recoveries of these compounds by SFE at 50°C and 30 MPa with CO2 (modified dynamically with methanol or statically with triethylamine) were 10 to 77% higher than those by Soxhlet or soni-cation with dichloromethane methanol (2 1). ASE at 150°C and 17 MPa with the same solvent mixture as Soxhlet showed the highest extraction efficiency among the extraction methods evaluated. SFE exhibited the best precision because no cleanup was needed, whereas Soxhlet, sonication, and ASE extracts required an alumina column cleanup prior to analysis. SFE and ASE used less solvent and reduced the extraction time by a factor of 3 and a factor of 20 compared to sonication and Soxhlet, respectively. 

Shaker table techniques have been developed with increased efficiency for acidic and basic compounds. The sample is placed in an extraction vessel (Erlenmeyer flask or glass jar) together with an extracting solvent, dichloromethane methanol H2SO4 (70 29 1) for acidic compounds or dichloromethane methanol NaOH (70 29 1) for basic compounds. The vessel is placed on a platform shaker for 1 h and then the liquid is decanted into a separatory funnel-containing water. The separatory funnel is gendy shaken, the layers are allowed to separate as for a normal liquid liquid extraction, and the solvent is collected for further processing. 

Different polar or nonpolar solvents - comparison of the extraction recovery Hexane, ethyl acetate, dichloromethane, methanol... 

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