Solutions by dilution

Separations based upon differences in the chemical properties of the components. Thus a mixture of toluene and anihne may be separated by extraction with dilute hydrochloric acid the aniline passes into the aqueous layer in the form of the salt, anihne hydrochloride, and may be recovered by neutralisation. Similarly, a mixture of phenol and toluene may be separated by treatment with dilute sodium hydroxide. The above examples are, of comse, simple apphcations of the fact that the various components fah into different solubihty groups (compare Section XI,5). Another example is the separation of a mixture of di-n-butyl ether and chlorobenzene concentrated sulphuric acid dissolves only the w-butyl other and it may be recovered from solution by dilution with water. With some classes of compounds, e.g., unsaturated compounds, concentrated sulphuric acid leads to polymerisation, sulphona-tion, etc., so that the original component cannot be recovered unchanged this solvent, therefore, possesses hmited apphcation. Phenols may be separated from acids (for example, o-cresol from benzoic acid) by a dilute solution of sodium bicarbonate the weakly acidic phenols (and also enols) are not converted into salts by this reagent and may be removed by ether extraction or by other means the acids pass into solution as the sodium salts and may be recovered after acidification. Aldehydes, e.g., benzaldehyde, may be separated from liquid hydrocarbons and other neutral, water-insoluble hquid compounds by shaking with a solution of sodium bisulphite the aldehyde forms a sohd bisulphite compound, which may be filtered off and decomposed with dilute acid or with sodium bicarbonate solution in order to recover the aldehyde. 

Prepare the wash solution by diluting 5mL of the 2 per cent quinoline hydrochloride solution with water to 200 mL. 

Stock solution. Prepare a 200- ug mL stock solution in ACN Fortification solutions. Prepare 0.04 and 0.2 lagmL fortification solutions by dilution of the stock solution in acetonitrile (trinexapac-ethyl). Prepare 0.05 and 0.25 j.gmL fortification solutions by dilution of the stock solution in water (trinexapac). 

Standard solutions. Prepare different concentrations of standard solutions by dilutions of the stock solution with the injection solution. 

Stock standard solution containing 1 mg mL mancozeb. Dissolve about 13.5 mg of mancozeb (taking into consideration the purity of the standard, which is about 74%) in 10 mL of 10% EDTA solution. Prepare this stock solution daily. Prepare working standard solutions by diluting appropriate volumes of the stock solution with 10% EDTA in order to obtain concentrations between 2.5 and 50 qg mL mancozeb. 

Prepare an HC1 solution by diluting 100 mL of concentrated HC1 with 44 mL of water. 

Prepare biotinylated secondary antibody solution by diluting 2 drops biotinylated antibody with 50 to 100 ml TTBS (nitrocellulose or PVDF) or TBS (nylon). 

Prepare a 1.0 mg/ml 5a-cholestane (>99% pure) stock standard solution in n-hex-ane. Store up to 3 months at 4°C. Prepare a working solution by diluting the stock solution to 0.2 mg/ml in dimethylformamide (DMF). Prepare fresh. 

Prepare a 20 mM TMP stock solution by accurately weighing 328 mg TMP (Sigma) into a 100-ml volumetric flask and diluting to mark with water for Basic Protocol 1 and Alternate Protocol 1 or 1 -butanol for Alternate Protocol 2 (20 mM malonal-dehyde final). Store up to 3 months at 4°C. Prepare a 0.2 mM working solution by diluting 100-fold in a volumetric flask. Store up to 1 month at 4°C. 

A secondaty standard solution is prepared from the above stock solution by diluting 1 mL to 100 mL ... 

Thiocyanate standard solns. 1.673 g potassium thiocyanate, KSCN in distilled water, diluted to 1 L. This stock soln. = 1000 mg SCN7L or 1 mL = 1 mg SCN". Prepare a secondary standard from the stock solution by diluting 1 mL stock solution to 100 mL with distilled water. Secondary std = 10 mg SCN-/L or 1 mL = 0.01 mg SCN". Prepare a series of calibration standards by diluting the secondary standard with distilled water as follows ... 

Procedure (a) Prepare an approximately 0.5N HC1 solution by diluting 21 cc. of 12 TV HC1 with 479 cc. of distilled water. After thoroughly mixing, store it in the glass-stoppered bottle. 

The compounds dissolved both in the spent calcium hydrogen carbonate solutions and in the sulphuric acid, such as mononitrophenols, dinitrophenols and picric acid, may be recovered by precipitation from the calcium hydrogen carbonate solution by acidification, and from sulphuric acid solution by dilution with water. 

These solutions were used for the preparation of the working solutions of docetaxel and paglitaxel. Solutions with a concentration of 250 nM, 1.25,5,12.5 and 25 pM docetaxel were prepared as calibration standard working solutions by dilution of the stock solution with a mixture of methanol/water 1 1. For the quality... 

Acidity (as acetic acid) Mix 38 mL of sample with an equal volume of carbon dioxide-free water, add 0.1 mL of phenol-phthalein TS, and titrate with 0.1 A sodium hydroxide. Not more than 0.1 mL is required to produce a pink color. Aldehydes (as formaldehyde) Prepare a Sample Solution by diluting 2.5 mL of sample with 7.5 mL of water. Prepare a Standard Solution containing 40 p,g of formaldehyde in 10 mL of water. Add 0.15 mL of a 5% solution of 5,5-dimethyl-1,3-cyclohexanedione in alcohol to each solution, and evaporate on a steam bath until the Acetone is volatilized. Dilute to 10 mL with water, and cool quickly in an ice bath while stirring vigorously. Any turbidity produced in the Sample Solution does not exceed that produced in the Standard Solution. 

Methanol Prepare a Sample Solution by diluting 10 mL of sample to 100 mL with water. Prepare a Standard Solution in water containing 40 p.g of methanol in each milliliter. Add 0.2 mL of 10% phosphoric acid and 0.25 mL of 1 20 potassium permanganate solution to 1 mL of each solution. Allow the mixtures to stand for 15 min, then add 0.3 mL of 1 10 sodium bisulfite solution to each, and shake until colorless. Slowly add 5 mL of ice-cold 80% sulfuric acid, keeping the mixtures cold during the addition. Add 0.1 mL of 1 100 chromotropic acid solution, mix, and digest on a steam bath for 20 min. 

Modifier Working Solution Weigh an amount of palladium nitrate equivalent to 1 g of palladium, and dilute to 100 mL with 15% nitric acid to make a stock solution. Just before use, prepare a Modifier Working Solution by diluting the stock solution 1 10 with water. 

Assay Solution Weigh and suspend 1.0 g of sample in 100 mL of water. Add 2 mL of 2 5 ammonium hydroxide. If the sample is not readily soluble, comminute to disperse it evenly in the liquid, then agitate vigorously and wash down the sides of the flask with 0.1 N ammonium hydroxide. Heat the mixture in an autoclave at 121° for 15 min. If lumping occurs, agitate the sample until the particles are evenly dispersed. Dilute the mixture with water to 200 mL. Filter through Whatman No. 1 filter paper, or equivalent, if necessary, to remove any undissolved particles. Adjust the filtered mixture to pH 6.8 and dilute to 1000 mL with water. Prepare the final Assay Solution by diluting 1.0 mL of the intermediate solution with water to a final volume of 50.0 mL. 

Standardization of Water Solution for Residual Titration Prepare a Water Solution by diluting 2 mL of pure water to 1000 mL with methanol or another suitable solvent. Standardize this solution by titrating 25.0 mL with the Karl Fischer Reagent, previously standardized as directed under Standardization of the Reagent. Calculate the water content, in milligrams per milliliter, of the Water Solution with the formula... 

Sulfuric Acid, Alcoholic, 0.5 N Add cautiously, with stirring, 13.9 mL of sulfuric acid to a sufficient quantity of absolute alcohol to make 1000.0 mL. Alternatively, prepare this solution by diluting 100.0 mL of 5 N Sulfuric Acid with absolute alcohol to make 1000.0 mL. 

Prepare an 250-units/ml phosphorylase kinase solution by diluting the stock enzyme 1 10 with reaction buffer. 

Prepare 50pgml-1 stock solutions by diluting 50ml of each l.OOOgl-1 solution to 11. 

Prepare a 5.000gAll-1 solution by dissolving clean aluminum metal in 100 ml of water containing 50 ml of 12 M HC1 and 10 ml of 16 M HN03. Cool the solution to room temperature and dilute to volume in a 1-1 volumetric flask. Make a 500/igAlml-1 stock solution by diluting a 100-ml aliquot to 11 in a volumetric flask. 

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