Extraction drying procedure

Hibbert and Burt dissolved the benzoylperoxide in dry ether, cooled to — 50 and added the calculated amount of a 10 per cent sodium ethylate solution, maintaining the low temperature during the procedure. Sufficient ice water was added to give a clear solution, the ether containing the ethyl benzoate separated and the aqueous sodium benzoylperoxide solution added slowly with stirring to twice the necessary amount of cold 20 per cent sulfuric acid (reaction mixture always at o°). The oily layer of benzoylhydroperoxide was then extracted three times with chloroform and the extract dried over anhydrous sodium sulfate. 

Preparation of cotton bract extracts. Figure 1 is a flow chart showing our procedures for preparing the various bract extracts. Dried bracts (frost killed) were hand picked just prior to harvest from cotton fields in the Lubbock, Texas area. These were stored at room temperature. Extracts were freeze-dried and stored at -4°C. For inhalation challenge by our subjects each extract was reconstituted with water or saline, as indicated, at a concentration equivalent to the standard crude extract. This Insured that for challenge purposes components were not concentrated as purification progressed. 

Methyl o-methoxyphenyl telluride (typical procedure). To a frozen solution of MeTeLi (50 mmol) is added o-bromoanisole (9.3 g, 50 mmol). The mixture is allowed to warm at room temperature, stirred for 1.5 h and then quenched with deoxygenated H2O (100 mL). The organic product is extracted with ether (3X50 mL), the organic extracts dried (MgS04) for 16 h and evaporated, and the residue is distilled under vacuum, giving the telluride as a pale yellow oil (9.3 g (74%)). 

Diacetoxylation of olefins with benzenetellurinic anhydride (typical procedure) To a solution of (PhTe0)20 (0.95 g, 2.1 mmol) in dry HOAc (15 mL) is added styrene (0.208 g, 2.0 mmol) in HOAc (4 mL) and 98% H2SO4 (0.020 g, 0.2 mmol) in HOAc (1 mL). The mixture is gently refluxed for 24 h, which turns red with deposition of a small amount of elemental tellurium. After removal of tellurium (0.071 g, 0.56 mmol) by fdtration, the solvent is evaporated, the residue extracted with ether and the ether extract dried (MgS04). Chromatography on Si02 gives the v/c-diacetate (0.363 g (82%)) and 1-phenylethyl acetate (0.029 g (9%)). 

The procedure can be interrupted at this point and the ether extracts dried over magnesium sulfate overnight in the refrigerator. 

To a solution of l,l,2,2-tetrafluoro-3-(tosyloxy)propane (0.86 g, 3 mmol) in THF was added dropwise 1.6M BuLi in hexane (4.1 mL, 6.6 mmol) at — 78°C over 20 min under argon. After lOmin at — 78 "C, the reaction was quenched with cold 10% aq HC1. Extraction, drying, concentration, and column chromatography (benzene) give a pale-yellow syrup yield (70%) (E/Z) 14 86. The procedure can also be applied to a 15-mmol scale. 

Determine the extractable contents of the analytes using the procedure described below. Carry out all extractions on air-dried sediment. Before subsampling, ensure the sample is suitably homogenised. Take the sample using a suitable (see Apparatus) plastic spatula. For each batch of extractions, dry a separate 1 g sample of the sediment in a layer of about 1 mm depth in an oven (105 2°C) to constant mass. From this, a correction to dry mass is obtained, which should be applied to all analytical values reported (i.e. results should be quoted as amount of metal per gram of dry sediment). Perform the extractions by shaking in a mechanical, end-over-end, shaker at a speed of 30 10 rpm and a room temperature of 22 5°C. Perform the sequential extraction according to the steps described below. 

Solvent Extraction. The procedures used are described elsewhere (9, 10). Although preliminary experiments showed that equilibrium was established within two hours, all samples were mixed for 24 hours. Duplicate 1-ml. aliquots of the organic phase were counted either in a well counter (for gamma emission) or as dry samples in a 2tt proportional counter (for beta emission). 

Ethanol/Benzene. The solubility of wood in EtOH/benzene (benzene is a known carcinogen toluene can be substituted) in a 1 2 volume ratio will give a measure of the extractives content. This procedure is Tappi Standard T 204 and ASTM Standard D 1107. The wood meal is refluxed 6-8 h in a Soxhlet flask, and the weight loss of the extracted, dried wood is measured. Sometimes the lignin, carbohydrate, and other components are determined on wood that has been extracted previously with EtOH/benzene (see Table XIII). 

Reductive desulphonylation of a-alkylidene fi-oxosulphones (typical procedure) To a solntion of NaTeH, prepared from tellurium (0.65 g, 5 mmol) and NaBH (0.45 g, 12 mmol) in EtOH (20 mL) under Nj, is added, while stirring, a solution of a-(p-bromoben-zylidene) )3-ketosulphone (0.73 g, 2 mmol) in DMF (15 mL). The solution, which immediately turns red-black, is stirred at room temperature for 3 h, and after addition of HjO (30 mL) is exposed to air for 30 min, to precipitate tellurium. The mixture is fdtered, the filtrate extracted with EtjO (3x40 mL) and the combined ether extracts dried (MgS04) and concentrated in vacuo to give the crude product, which is purified by SiOj chromatography (elution with benzene/EtOAc, 10 1), giving pure 2-(p-bromophenyl)ethyl phenyl ketone (0.46 g (80%) m.p. 65-66°C). 

At the end of the extraction, the extracted fat was reconstituted in a previously tared automatic sampler vial using methylene chloride. The methylene chloride was evaporated to leave a dry fat extract which was then weighed. For the development of this method, the appropriate combination of chopping and drying procedures was explored in a series of experiments. These are outlined in Table 1. 

Analytically determined concentrations of 2,6-DNT and 2-A-6-NT, as well as picric acid, in marine sediments were much lower when samples were dried at room temperature and extracted with acetonitrile [12] according to standard procedures for soils and sediments [19], than when sediments were not dried prior to extraction [12], A portion of the parent compounds could be transformed during the drying procedure, and the authors suggested that sediments contaminated with explosives should not be air-dried prior to extraction for chemical measurements. 

One of the most critical steps in the analysis of procyanidins is their extraction. Preservation procedures and storage conditions of the crude samples as well as procedures and conditions during homogenization and extraction have a tremendous impact on the amount and composition of the extractable procyanidins. In view of a good reproducibility a complete standardization of all procedures and experimental conditions from the time of sample collection to the storage of the final extract must be emphasized. It is recommended to analyze fresh samples. If this is not possible, lyophilization is the drying procedure of choice. Samples should not be stored at all. If this can not be avoided care must be taken to exclude... 

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