Extraction buffer, solution preparation

A solution prepared of 19-methanesulfonate (68b 2.45 g) and buffered acetolysis solution (120 ml) is heated at 100° for 16 hr. The product (2.17 g of orange oil) is isolated by ether extraction in the following manner. The reaction mixture is cooled to room temperature and shaken with a mixture of ether (600 ml) and water (1 liter). The aqueous phase is separated and extracted with ether (600 ml). The ether solutions are washed separately with water (two and three 500 ml portions respectively) then combined and... 

The specifications and standardization include raw materials, preparation method of the standard solution, concentration of proteins, and the main band on SDS-PAGE. The outline of the procedure for preparation of the calibrators is shovm in Eig. 4.2. Table 4.5 shows the raw materials and the preparation method of the initial extract. To prepare the calibrators, the raw materials are extracted by the standard solution containing SDS and mercaptoethanol. The initial extract is prepared by centrifugation and filtration of the extract. The diluted extract is then prepared by 10-fold dilution of the initial extract with phosphate-buffered saline (PBS pH 7.4). The protein concentration of the diluted extract is assayed using the 2-D Quant kit (Amersham Bio Sciences). The standard solution is then... 

Transfer the residue prepared as in Section 6.1.1 into a 300-nL separatory funnel with 25 mL of phosphate buffer solution (0.1 M, pH 7.4). Add 10 mL of saturated aqueous sodium chloride and 50 mL of 0.5 M sodium hydrogen carbonate to the funnel and shake the funnel vigorously for 1 min. Add 70 mL of ethyl acetate to wash the aqueous layer to the funnel, shake, separate, and discard the ethyl acetate layer. Repeat this extraction procedure three times. Add 2 mL of phosphoric acid and 20 mL of an acetate buffer solution (0.1 M, pH 4) to the aqueous layer and extract the mixmre with 50 mL of ethyl acetate three times. Combine the extracts and filter into a 500-mL round-bottom flask through 60 g of anhydrous sodium sulfate supported by a plug of cotton wool in a funnel. Concentrate the filtrate to dryness under reduced pressure. 

Sample preparation techniques vary depending on the analyte and the matrix. An advantage of immunoassays is that less sample preparation is often needed prior to analysis. Because the ELISA is conducted in an aqueous system, aqueous samples such as groundwater may be analyzed directly in the immunoassay or following dilution in a buffer solution. For soil, plant material or complex water samples (e.g., sewage effluent), the analyte must be extracted from the matrix. The extraction method must meet performance criteria such as recovery, reproducibility and ruggedness, and ultimately the analyte must be in a solution that is aqueous or in a water-miscible solvent. For chemical analytes such as pesticides, a simple extraction with methanol may be suitable. At the other extreme, multiple extractions, column cleanup and finally solvent exchange may be necessary to extract the analyte into a solution that is free of matrix interference. 

Homogenize 50 g of a prepared sample with a solution containing 50 mL of borate buffer (pH 10) and 50 mL of acetone in a blender for 5 min. Pour the homogenate into an Erlenmeyer flask, add 50 mL of acetone and shake the flask for 10 min using a shaker. Filter the aqueous acetone extract through a 25G-4 glass filter overlaid with 3 g of Celite. Wash the residue on the filter with 50 mL of acetone. Combine the filtrates and remove acetone by rotary evaporation. Transfer the residue with 5 mL of 4% sodium dodecyl sulfate aqueous solution into a separatory funnel, extract the solution with two portions of 50 mL of dichloromethane and collect the organic... 

The cholinesterase to determine the toxic activity may be chosen (i) in pure form of commercial enzyme from animals in a water buffer solution or using biosensors, enzyme preparation impregnated into a rigid matrix that significantly activates the enzymic activity and (ii) in the form of crude extracts from plant or animal tissues. 

This preparative scheme leads to only 30% yield due to the side reactions between the meto-astatoaniline diazonium salt and astato-phenol, which cannot be eliminated even by continuous extraction of the product with n-heptane (167). All the astatophenols synthesized to date have been identified by either HPLC (99,104) or TLC (160,166,167). Their dissociation constants (KJ have been established from extraction experiments by measuring the relative distribution of compounds between aqueous borax buffer solutions and n-heptane as a function of acidity. On the basis of these derived values, the Hammett a-constants and hence the field (F) and resonance (R) effects have been estimated for these compounds (167) (see Table VI). The field effect for astatine was found to be considerably weaker than that for other halogens the resonance effect was similar to that for iodine (162). 

Preliminary Purification of Dandelion and Sweet Corn. The plant extract in pH 7 buffer was sealed in a Visldng cellulose dialysis membrane bag, immersed in a volume of aqueous pH 7 buffer equal to twice the volume of its contents, and shaken for at least 2 hours. The outside solution was replaced, and die entire operation repeated twice. The three outside buffer solutions were combined. A dialysis blank was prepared in similar fashion. The dialyzate was washed once with ethyl acetate. The aqueous phase was adjusted to pH 2 with sulfuric acid and extracted several times with ethyl acetate. The combined ethyl acetate extracts were evaporated to dryness, and redissolved in a small volume of methanol. 

Turning to assays using sensors that require more than a simple cut in the sample, Bergann et al. [37] paid considerable attention to sample preparation in attempts to measure lactate in meat with a sensor (not thick film) based on reaction of hydrogen peroxide with a platinum electrode or on the reaction of ferrocene carboxylate with the active site of lactate oxidase. Sample preparation entailed extraction into buffer following grinding. In some cases, ground samples were left to allow the lactate to diffuse into the buffer solution. This was quite effective but slow (up to 90 min). Ultimately, the quality of the assay was dependent on the method of sample preparation. 

Hydrolysis on a preparative scale and separation. A sample of spruce wood or pulp (300g), suspended in 6 litres of buffer solution, was refluxed for 19 hours. The resulting aqueous phase was filtered and concentrated to about 200 ml by evaporation at 40 °C under reduced pressure. The concentrated aqueous phase was extracted with... 

The new system was applied for standard ethanol solutions prepared in phosphate buffer solutions (pH 7.0). Extracted ethanol solutions were also used with 10% (w/v) NaCl by NBR 13992 1997 from gasohol blends (12) (Brazilian Association Technical Standard). Table 3 shows the concentrations of the extracted ethanol solutions measured by HPLC and respective gasoholblends. This new integrated system biosensor-FIA was used for the range of 0.05-1.5 g of ethanol/L, and good results were obtained compared with the ethanol content measured by the HPLC standard method. 

Difluoromethoxy-2-[(4,5-dimethoxy-2-pyridyl)methylthio]-lH-benzimidazole (about 1 g) are dissolved in 10 ml of dioxane and 2 ml of 1 N sodium hydroxide solution. An equimolar amount of a titrated aqueous sodium hypochlorite solution, to which 1 mole per liter of sodium hydroxide solution has been added, is first added dropwise, while cooling with ice. After one hour a further equivalent and after 3 hours half the equimolar amount of sodium hypochlorite are added, to achieve complete reaction. After a reaction time of 4 hours, 5 ml of 5% strength sodium thiosulfate solution and another 25 ml of dioxane are added and the upper dioxane phase is separated off, washed once with 5 ml of sodium thiosulfate solution and concentrated on a rotary evaporator. The oily residue is dissolved in 20 ml of water and 10 ml of ethyl acetate and the solution is brought to pH 7 with about 100 ml of a buffer solution of pH 6.8. The solid which has precipitated out is filtered off with suction over a suction filter, washed with water, extracted by stirring at OC with acetone and dried. 5-Difluoromethoxy-2-[(4,5-dimethoxy-2-pyridyl)methanesulfinyl]-lH-benzimidazole is prepared yield about 85%. 

To localize the precursors of Acp, the low molecular weight compounds present in yeast cells were isolated by cell disruption, centrifugation and ultrafiltration (Schieberle, P., in preparation). Boiling and continous extraction of a phosphate buffer solution containing the compounds of a molecular weight lower than 1000 produced substantial amounts of Acp. Furthermore, the free proline content of the yeast used in these experiments was analysed and calculated to be more than 200 mg/kg yeast. 

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