Extraction, Soxhlet


Soxhlet Extraction. Occasionally a crude product (often of natural occurrence) is obtained, from which a particular component may be isolated by repeated extraction with a hot soK-ent. For this purpose, Soxhlet s Extraction Apparatus (Fig. 19) is usually employed.  [c.37]

For extraction purposes, a Soxhlet apparatus (Fig. 23(H)) can be inserted between a flask of boiling solvent and the reflux condenser A above. This apparatus is similar in design to that shown in Fig. 19, p. 3b in the type shown in Fig. 23(H) the hot extract continuously overflows through the side- tube into the boiling solvent below, but the syphon type shown in Fig. 19 is also available.  [c.47]

For separation by Soxhlet extraction, see p. 38.  [c.398]

Solids by solvents. The various forms of Soxhlet apparatus illus trated in Section 11,44 can be purchased with ground glass joints. A simplified form, in which the fragile side tubes are absent, is shown in Fig. II, 58, 1. The material to be extracted, if of granular form, may rest upon a sintered glass disc or upon a removable septum  [c.222]

Soxhlet Extraction. Occasionally a crude product (often of natural occurrence) is obtained, from which a particular component may be isolated by repeated extraction with a hot solvent. For this purpose, Soxhiet s Extraction Apparatus (Fig. 19) is usually employed.  [c.37]

For extraction purposes, a Soxhlet apparatus (Fig. 23(H)) can be inserted between a flask of boiling solvent and the reflux condenser A above. This apparatus is similar in design to that shown in Fig. 19, p. 38 in the type shown in Fig. 23(H) the hot extract continuously overflows through the side-tube into the boiling solvent below, but the syphon type shown in Fig. 19 is also available.  [c.47]

For separation by Soxhlet extraction, see p. 38.  [c.398]

In a solid-phase extraction the analytes are first extracted from their solution matrix into a solid adsorbent. After washing to remove impurities, the analytes are removed from the adsorbent with a suitable solvent. Alternatively, the extraction can be carried out using a Soxhlet extractor.  [c.224]

Several standard methods for the quantitative analysis of food samples are based on measuring the sample s mass following a selective solvent extraction. For example, the crude fat content in chocolate can be determined by extracting with ether for 16 h in a Soxhlet extractor. After the extraction is complete, the ether is allowed to evaporate, and the residue is weighed after drying at 100 °C. This analysis has also been accomplished indirectly by weighing a sample before and after extracting with supercritical GO2.  [c.264]

Extraction of samples usiag supercritical fluids is becoming an accepted method for gas chromatography (gc) sample preparation, especially ia the environmental field (75). For example, the U.S. Environmental Protection Agency has a method (SW 846 3561) that uses supercritical fluids as the extracting solvent for the removal of polyaromatic hydrocarbons (PAHs) from sod. The efficacy of extraction is comparable to organic solvent extraction but much less time is required. Extraction usiag an SCF can save 5.5 hours if used iastead of a 14-step Hquid separatory funnel extraction it can save 48 hours if used iastead of a Soxhlet extractioa employing rotary evaporatioa (76).  [c.226]

Supercritical Fluid Extraction. Polycychc aromatic hydrocarbons (PAHs) have been extracted from contaminated land samples by supercritical fluid extraction (SEE) with both pure and modified carbon dioxide (35) (see Supercritical fluids). An experimental design approach, based on central composite design, was used to determine which SEE variable affects the total recovery of 16 PAHs. Pour parameters were chosen for evaluation pressure, temperature, extraction time, and percentage of methanol modifier addition. Accessible levels of each parameter were dependent on instmmental constraints. A statistical treatment of the results indicated that extraction time and percentage of modifier addition were the only variables to affect PAH recovery significantly. The levels of these variables were set at the maximum values while the pressure and temperature were maintained at their midpoint value in design. These conditions were used in a repeatabiUty study n = 7), which extracted an average of 458.0 mg/kg total PAHs from the contaminated land sample with a relative standard deviation (RSD) of 3.1%. Sequential extractions on three of these samples, using identical operating conditions, did not show the presence of PAHs. The results were compared with the Soxhlet extraction and micro wave-assisted (MAE) extraction of the sample, which recovered an average of 297.4 (RSD 10.0%) and 422.9 (RSD 2.4%) mg/kg, respectively.  [c.242]

Ash is a measure of residual sodium acetate. A simple method consists of dissolving the PVA in water, diluting to a known concentration of about 0.5 wt %, and measuring the electrical conductivity of the solution at 30°C. The amount of sodium acetate is estabUshed by comparing the result to a cahbration curve. A more lengthy method involves the extraction of the PVA with methanol using a Soxhlet extractor. The methanol is evaporated and water is added. The solution is titrated using hydrochloric acid in order to determine the amount of sodium acetate.  [c.487]

Analytical Supercritical Fluid Extraction and Chromatography Supercritical fluids, especially CO9, are used widely to extrac t a wide variety of solid and hquid matrices to obtain samples for analysis. Benefits compared with conventional Soxhlet extraction include minimization of solvent waste, faster extraction, tunabihty of solvent strength, and simple solvent removal with minimal solvent contamination in the sample. Compared with high-performance liquid chromatography, the number of theoretical stages is higher in  [c.2004]

In a solid-phase extraction the analytes are first extracted from their solution matrix into a solid adsorbent. After washing to remove impurities, the analytes are removed from the adsorbent with a suitable solvent. Alternatively, the extraction can be carried out using a Soxhlet extractor.  [c.224]

Several standard methods for the quantitative analysis of food samples are based on measuring the sample s mass following a selective solvent extraction. For example, the crude fat content in chocolate can be determined by extracting with ether for 16 h in a Soxhlet extractor. After the extraction is complete, the ether is allowed to evaporate, and the residue is weighed after drying at 100 °C. This analysis has also been accomplished indirectly by weighing a sample before and after extracting with supercritical CO2.  [c.264]

It may be better to carry out the extraction in a Soxhlet apparatus or an apparatus of the type described in Org. Syn. 2, 49.  [c.61]

Soxhlet thimbles and filter papers may contain traces of lipid-like materials. For manipulations with highly pure materials, as in trace-pesticide analysis, thimbles and filter papers should be thoroughly extracted with hexane before use.  [c.3]

Trace impurities in silica gel for TLC can be removed by heating at 300° for 16h or by Soxhlet extraction for 3h with distilled chloroform, followed by 4h extraction with distilled hexane.  [c.3]

For extraction of solid materials with a solvent, a Soxhlet extractor is commonly used. This technique is applied, for example, in the alcohol extraction of dyes to free them from insoluble contaminants such as sodium chloride or sodium sulfate.  [c.7]

Cobalt (II) meso-5.10,15,20-tetraphenylporphine complex [14172-90-8] M 671.7. Brown crystals from Et20 or CHCl3-MeOH (cf iron chloride complex). Recrystd by extraction (Soxhlet) with CgHg. Sol in most organic solvents except MeOH and pet ether. [UV, IR J Am Chem Soc 70 1808 7948 81 5111 7959.]  [c.413]

The experimental conditions for conducting the above reaction in the presence of dimethylformamide as a solvent are as follows. In a 250 ml. three-necked flask, equipped with a reflux condenser and a tantalum wire Hershberg-type stirrer, place 20 g. of o-chloronitrobenzene and 100 ml. of diinethylform-amide (dried over anhydrous calcium sulphate). Heat the solution to reflux and add 20 g. of activated copper bronze in one portion. Heat under reflux for 4 hours, add another 20 g. portion of copper powder, and continue refluxing for a second 4-hour period. Allow to cool, pour the reaction mixture into 2 litres of water, and filter with suction. Extract the solids with three 200 ml. portions of boiling ethanol alternatively, use 300 ml. of ethanol in a Soxhlet apparatus. Isolate the 2 2- dinitrodiphenyl from the alcoholic extracts as described above the 3ueld of product, m.p. 124-125°, is 11 - 5 g.  [c.528]

The high sodium ion concentration results in facile crystallisation of the sodium salt. This process of salting out with common salt may be used for recrystallisation, but sodium benzenesulphonate (and salts of other acids of comparable molecular weight) is so very soluble in water that the solution must be almost saturated with sodium chloride and consequently the product is likely to be contaminated with it. In such a case a pure product may be obtained by crystallisation from, or Soxhlet extraction with, absolute alcohol the sul-phonate is slightly soluble but the inorganic salts are almost insoluble. Very small amounts of sulphones are formed as by-products, but since these are insoluble in water, they separate when the reaction mixture is poured into water  [c.548]

The experimental details for mono-M-propylanillne are as follows. Reflux a mixture of 230 g. of aniline and 123 g. of n-propyl bromide for 8-10 hours. Allow to cool, render the mixture alkafine, and add a solution of 150 g. of zinc chloride in 150 g. of water. Cool the mixture and stir after 12 hours, filter at the pump and drain well. Extract the thick paste several times with boiling light petroleum, b.p. 60-80° (it is best to use a Soxhlet apparatus), wash the combined extracts successively with water and dilute ammonia solution, and then dry over anhydrous potassium carbonate or anhydrous magnesium sulphate. Remove the solvent on a water bath, and distil the residue from a Claisen flask with fractionating side arm (well lagged). Collect the n-propyl-aniline at 218-220° the yield is 80 g. Treat the pasty solid zincichloride with an excess of. sodium hydroxide solution and steam distil 130 g. of pure aniline are recovered.  [c.571]

Dissolve 68 g, of crystallised sodium acetate in 100 ml. of water, and dilute to 120 ml. Add 50 ml. of this solution to the reaction mixture and stir for a further 4 hours eUminate any appreciable amoimt of foamy solid by the addition of a few drops of ethyl acetate. Allow the mixture to stand overnight in an ice box or in a refrigerator the temperature must be kept below 7°. Then add the remainder of the sodium acetate solution with stirring to the mixture cooled in an ice bath, stir for an additional period of 2-3 hours, and allow the temperature to rise to 20-25° during 24 hours. Introduce just sufficient sodium hydroxide solution with stirring to cause the mixture to have a distinct odour of dimethylaniline (24 ml. of a 40 per cent, solution are usually required), and allow to stand at room temperature (20-25°) for 48 hours or longer. (The formation of the azo compound is a very slow reaction, but is accelerated by increasing the pH of the solution.) Filter off the sohd at the pump, wash it first with water, then with 40 ml. of 10 per cent, acetic acid (to remove the dimethylanihne), and finally with water (the last filtrate is pale pink) drain well. Dry the sohd in the air for 24 hours. Suspend the sohd in 400 ml. of methyl alcohol in a 1500 ml, bolt-head flask stir the mixture on a water bath under a reflux condenser for 1 hour, cool in ice and filter. Wash with 400 ml. of cold methyl alcohol and dry in the air. The yield of crude methyl red is 85 g. (2). Purify by extraction with 700 ml. of boiling toluene (3) in a Soxhlet apparatus (Fig. II, 44, 5 or 6). When the extraction is complete, remove the flask containing the almost boihng toluene to a bath containing water at 90-100° and arrange that the level of the water is shghtly above that of the toluene in the flask. The temperature thus falls slowly and large crystals are obtained. Finally allow to cool to room temperature. Filter off the crystals and wash with a Uttle toluene. The yield of methyl red, m.p. 181-182°, is 79 g.  [c.626]

The experimental conditions for the reduction are similar to those for the Grignard reaction. For compounds which are readily soluble in ether, a solution of the compound in dry ether is added to an ethereal solution of lithium aluminium hydride (excess) at such a rate that the reaction mixture boils gently. When the reduction is complete, the excess of the reagent is decomposed by the cautious addition of moist ether, an ethanol-ether mixture or by the dropwise addition of cold water with vigorous stirring when water is used, it is desirable to employ a large flask because of the foaming which takes pleice. On the whole it is best to employ ethyl acetate, as its reduction product (ethanol) does not interfere in the subsequent isolation and no hydrogen is evolved. The reaction mixture is then poured gradually into excess of ice-cold dilute sulphuric acid to decompose the complex aluminium compounds and to dissolve the precipitated aluminium hydroxide the product is usually in the ethereal layer but, if it is water-soluble, must be isolat from the aqueous solution. For bases, after extraction of any neutral or acidic products, the solution is rendered alkaline with ION sodium hydroxide and the whole (including the precipitated aluminium hydroxide) is extracted with ether. For compounds which are slightly or sparingly soluble in ether, a Soxhlet apparatus is inserted between the flask and the reflux condenser and the compound is placed in the Soxhlet  [c.878]

A solution of 2,3-dimethylindole (145 g, 1 mol) in dry dioxan containing hydroquinone (100 mg) was treated with JV,JV,JV-trimethylbenzylammonium ethoxide (5 ml of a 40% solution in MeOH) and warmed to 35 C. Freshly distilled acrylonitrile (150 ml, 2.5 mol) was added at a rate such that the temperature did not rise above 40°C. The solution was then stirred overnight and diluted with 10% aq. acetic acid (11). The solution was extracted with CH Clj and the extract was washed with water and dried (MgS04). extract was then mixed with silica gel (800 g) and the solvent removed in vacuo. The silica was placed in a Soxhlet extractor and extracted with cyclohexane. The extract deposited the product as colourless needles (125 g, 63% yield).  [c.91]

Preparing the Sample Flame and electrothermal atomization require that the sample be in a liquid or solution form. Samples in solid form are prepared for analysis by dissolving in an appropriate solvent. When the sample is not soluble, it may be digested, either on a hot plate or by microwave, using HNO3, H2SO4, or HCIO4. Alternatively, the analyte may be extracted via a Soxhlet extraction. Liquid samples may be analyzed directly or may be diluted or extracted if the matrix is incompatible with the method of atomization. Serum samples, for instance, may be difficult to aspirate when using flame atomization and may produce unacceptably high background absorbances when using electrothermal atomization. A liquid-liquid extraction using an organic solvent containing a chelating agent is frequently used to concentrate analytes. Dilute solutions of Cd +, Co +, Cu +, Fe +, Pb +, Nb+, and Zn +, for example, can be concentrated by extracting with a solution of ammonium pyrrolidine dithiocarbamate in methyl isobutyl ketone.  [c.418]

Microwave-Assisted Extraction. Sample preparation techniques that prevent or minimize pollution in analytical laboratories, improve target analyte recoveries, and reduce sample preparation costs were evaluated with regard to the microwave-assisted extraction (MAE) procedure for 187 compounds and four Aroclors Hsted in EPA Methods 8250, 8081, and 8141A (38) (see Microwave technology). The results indicate that most of these compounds can be recovered in good yields from the matrices investigated. Eor example, recoveries ranged from 80 to 120% for 79 of the 95 compounds Hsted in Method 8250 38 of the 45 organochlorine pesticides Hsted in Method 8081 and 34 of 47 organophosphoms pesticides Hsted in Method 8141A. When recoveries from freshly spiked oil samples were compared with those of aged samples, it was found that recoveries usually decreased in the aged samples. There was more spread in recoveries with increased aging time. Eor 15 compounds in a reference soil, the recoveries of 14 compounds by MAE were equal to or better than recoveries obtained by Soxhlet extraction (naphthalene was an exception). Eor selected organochlorine pesticides, recoveries from spiked oil samples were at least 7% higher for MAE than for either Soxhlet or sonication extraction.  [c.242]

PCBs and OCPs were identified and their concentrations determined by GC/MS in 14 samples of muscle tissue of fishes (pikes and pike-perches), caught in the Dnieper river and its tributaries. To obtain a representative data, the tissues of 3 fishes were united in 1 sample for each from 14 places of sampling. Homogenized muscle tissue (10.00 g) was mixed with anhydrous copper sulfate and extracted in Soxhlet appai atus for 24 h with dichloro-methane, or accelerated solvent extraction was used at the temperature 80 °C and step gradient of solvents diethyl ether, dichloromethane, and mixture of benzene/methanol (9/1). Extracts of muscle tissue of fishes were evaporated and redissolved in hexane. Then a sulfuric acid cleanup was performed. The samples, cleaned in this manner, were additionally purified using one of the two methods oleum treatment or micropreparative isolation of fraction, containing PCBs and OCPs, on the reverse phase HPLC column (C g). For the purpose of tai get compound losses evaluation during sample preparation procedure, samples were spiked with 200 ng per sample of 2,3,324,425-hexaclorobiphenyl (internal standard). Method blanks were carried out for each batch of samples. The samples were concentrated to 100 p.1 and analyzed on the gas chromatograph HP 5890 equipped with HP 5972 MSD in SIM mode. The instrument was calibrated using mixtures Aroclor 1221, 1242, 1254 and 16 OCPs. In all analyzed samples concentrations of DDT and its isomers, DDE, DDD, and PCBs (tri-, tetra-, penta-, hexa-, hepta-, octachloroisomers) were determined. Method detection limit for total PCBs content was 100 pg/kg (wet tissue) and for OCPs -20 pg/kg. Recoveries for accelerated solvent extraction ranged from 75 to 115 % as compai ed to Soxhlet extraction.  [c.235]

Preparing the Sample Flame and electrothermal atomization require that the sample be in a liquid or solution form. Samples in solid form are prepared for analysis by dissolving in an appropriate solvent. When the sample is not soluble, it may be digested, either on a hot plate or by microwave, using HNO3, H2SO4, or HCIO4. Alternatively, the analyte may be extracted via a Soxhlet extraction. Liquid samples may be analyzed directly or may be diluted or extracted if the matrix is incompatible with the method of atomization. Serum samples, for instance, may be difficult to aspirate when using flame atomization and may produce unacceptably high background absorbances when using electrothermal atomization. A liquid-liquid extraction using an organic solvent containing a chelating agent is frequently used to concentrate analytes. Dilute solutions of Cd, Co ", Cu ", Fe ", Ni ", and Zn ", for example, can be concentrated by extracting with a solution of ammonium pyrrolidine dithiocarbamate in methyl isobutyl ketone.  [c.418]

If the solution contains extraneous coloured material likely to contaminate the crystals, this can often be removed by adding some activated charcoal (decolorising carbon) to the hot, but not boiling, solution which is then shaken frequently for several minutes before being filtered. (The large active surface of the carbon makes it a good adsorbent for this purpose.) In general, the cooling and crystallisation steps should be rapid so as to give small crystals which occlude less of the mother liquor. This is usually satisfactory with inorganic material, so that commonly the filtrate is cooled in an ice-water bath while being vigorously stirred. In many cases, however, organic molecules crystallise much more slowly, so that the frltrate must be set aside to cool to room temperature or left in the refrigerator. It is often desirable to subject material that is very impure to preliminary purification, such as steam distillation, Soxhlet extraction, or sublimation, before recrystallising it. A greater degree of purity is also to be expected if the crystallisation process is repeated several times, especially if different solvents are used. The advantage of several crystallisations from different solvents lies in the fact that the material sought, and its impurities, are unlikely to have similar solubilities as solvents and temperatures are varied.  [c.14]

Water-soluble salts are best purified by preparing a concentrated aqueous solution to which, after decolorising with charcoal and filtering, ethanol or acetone is added so that the salts crystallise. They are collected, washed with aqueous ethanol or aqueous acetone, and dried. In some cases, water-soluble salts can be recrystallised satisfactorily from alcohols. Water-insoluble salts are purified by Soxhlet extraction, first with organic solvents and then with water, to remove soluble contaminants. The purified salt is recovered from the thimble.  [c.68]

Amberlite IRA-904 Anion exchange resin (Rohm and Haas) [9050-98-0]. Washed with IM HCl, CH3OH (1 10) and then rinsed with distilled water until the washings were neutral to litmus paper. Finally extracted successively for 24h in a Soxhlet apparatus with MeOH, benzene and cyclohexane [Shue and Yan Anal Chem 53 2081 1981]. Strongly basic resin also used for base catalysis [Fieser Fieser Reagents for Org Synth 1511, Wiley 1967].  [c.102]

V-(3-Bromopropyl)phthalimide [5460-29-7] M 268.1, m 72-74 , 74 . Place in a Soxhlet and extract with Et20, whereby the bis-phthalimido impurity is not extracted. Evaporate the Et20 and recryst from EtOH or aqueous EtOH or pet ether. [Chem Ber 21 2669 1888 Justus Liebigs Ann Chem 614 83 1958 Can J Chem n 1060 7955.]  [c.141]


See pages that mention the term Extraction, Soxhlet : [c.476]    [c.368]    [c.397]    [c.123]    [c.154]    [c.550]    [c.551]    [c.880]    [c.397]    [c.60]    [c.346]    [c.121]    [c.135]    [c.120]   
Practical organic chemistry (1960) -- [ c.37 , c.47 ]