Acetic acid buffer mixture

One mol of 2,6-xylidine is dissolved in 800 ml glacial acetic acid. The mixture is cooled to 10°C, after which 1.1 mol chloracetyl chloride is added at one time. The mixture is stirred vigorously during a few moments after which 1,000 ml half-saturated sodium acetate solution, or other buffering or alkalizing substance, is added at one time. The reaction mixture is shaken during half an hour. The precipitate formed which consists of cj-chloro-2,6-di-methyl-acetanilide is filtered off, washed with water and dried. The product is sufficiently pure for further treatment. The yield amounts to 70 to 80% of the theoretical amount. 

Mixture of acids and bases Various Phosphate buffer, 1% acetic acid (buffered to pH 3.0)... 

Electrochemical reduction of benzylic nitro compounds (27) in an ethanolic aqueous acetic acid buffer (35 65) affords a mixture of the corresponding oxime and hydroxylamine (equation 6)48. The hydroxylamine can subsequently be oxidized back to the oxime (28) (via the intermediate nitroso compound) conversions as high as 90% can be obtained. 

Perfetti et al. (131) described a method for the determination of ethoxyquin in milk. Milk solids were precipitated by adding acetonitrile, and the water-acetonitrile supernatant was washed with hexane to remove fat. The addition of NaCl caused the water-acetonitrile solution to separate into an aqueous phase and an acetonitrile phase, thus separating ethoxyquin from most water-soluble impurities. A large volume of water was then added to the acetonitrile layer, and ethoxyquin was partitioned into hexane and removed at reduced pressure. The residue was dissolved in the mobile phase and analyzed on a 250-mm X 4.6-mm-ID. Ultrasphere ODS column using fluorescence detection with excitation of 230 nm, and emission of 418 nm, respectively. A mixture of water and acetonitrile with a diethylamine-acetic acid buffer was the mobile phase. Recoveries from milk samples fortified at 1, 5, and 10 ng/g averaged 78%, with a coefficient of variation of 5.0%. Low concentrations (less than 1 ng/g) of apparent ethoxyquin were detected in commercial milk samples analyzed by this method. 

A hydrazide may also condense to some extent with an intermediate nitroso group,89 but the yield obtained so far is low. o-Nitrobenzoic hydrazide (70) is reduced in acetic acid buffer to a mixture from which some benzo-l,2,3-triazinone-4 (71) has been isolated. 

In 1947, Hudson et al. (H15) developed a method for acid phosphatase which, like the procedure of Bessey et al. for alkaline phosphatase (B16), was based upon the use of p-nitrophenyl phosphate as substrate. The buffer substrate solution consisted of equal volumes of a 0.1 M sodium acetate-acetic acid buffer, pH 5.4, and 0.001 M magnesium chloride and of a 0.4% solution of approximately 50% pure disodium p-nitrophenyl phosphate in 0.001 N HCl. To 1 ml of this solution, 0.1 ml of the serum sample was added. The final concentrations in this reaction mixture were 0.045 M acetate buffer, pH 5.4 magnesium chloride. 0.00045 ilf substrate, 0.004 M. The reaction was allowed to run for 30 minutes at 38°C, and the reaction was stopped by the addition of sodium hydroxide. The liberated yellow p-nitrophenol was read at 400 nm and the amount was... 

Because of the results found with p-(chloromercuri)benzoate and because /3-galactosidase is believed to be a sulfhydryl enzyme, it seemed advisable to investigate the effects of other sulfhydryl reagents. Virtually no inhibition of /3-galactosidase was found in the presence of iodoacetam-ide (9 X 10 M) over a period of 7 hours. A -Phenylmaleimide, at concentrations as high as 8.7 X 10 M, produced less than 10 % inhibition over a 20-hour period. However, when the concentration of V-phenyl-maleimide was raised to 9.1 X 10 M, assay of the incubation mixture revealed that 50% inhibition of /3-galactosidase occurred within a 2-hour period when the experiment was performed in 2-amino-2-(hydroxymethyl)-1,3-propanediol— acetic acid buffer, pH 8.0. Virtually no activity was lost when the latter experiment was repeated in phosphate buffer (Na salts) at the same pH. 

An alternative isolation procedure may be employed if the protein derivative is partially soluble in the aqueous ethanol. The pH of the reaction mixture is lowered to 8 by the careful addition of 1 M acetic acid. The mixture is filtered, and the filtrate, containing the protein derivative, is dialyzed against 0.01 M potassium phosphate buffer pH 8, at 4°C, followed by exhaustive dialysis against water, and by lyophiliza-tion. 

Thus, a sodium acetate-acetic acid buffer s capacity is maximum when equimolecular concentrations are taken in their mixture the pH becomes 4.74 (for Ka = 1.82 x 10 ). When the ratio salt/acid is varied, the buffer will have a different pH, but not far away from the value of pKa. The maximum variation in the acid salt ratio allowed is 1 10 or 10 1. The limiting values of the buffer pH becomes... 

Electrolyte Acetic Acid (buffer) (reducing) Oxelic Acid (buffer) dil. Acid (cold) Acid (hot) Mixtures (fHF) Cheieting Agents Basic Soins Fusion (f Acid leach) MgCI2 HO Ac HOAc/OAc- m.mu ... 

Solutions containing a mixture of a weak acid and one of its salts, or a weak base and one of its salts, are known as buffer solutions. The important property of a buffer solution is that its hydrogen-ion concentration does not change very much if small amounts of acids or bases are added to the solution. In the acetate-acetic acid buffer, for example, the concentrations of CH3COOH and CH3COO" are a good deal larger than the concentration of H ions. Thus, for the buffer solution just considered,... 

Take 100 mg of the product powder, dissolve it in 2 mL of 50 mmol/L acetic acid buffers (pH 6), and add sufficient quantities of a-Gal (50 nkat) and stir to dissolve. The reaction temperature is 30°C, reaction time is 36 h and the shaking speed is 100 r/min. After the enzymatic reaction, put the container into boiling water bath for 10 min and the a-Gal can be fiiUy inactivated. Add a certain amount of ultra-pure water to the inactivated mixture, and transfer into the centrifuge tube and centrifuge at 5,000 r/min for 5 min. Take the supernatant for HPLC analysis. The results are shown in Fig. 4.17. 

Volatile buffers with a pH ranging from 2.0 to 9.0 are generally utilized in PE. Typically, a formic acid/acetic acid/water mixture at pH 2.0 is used for nucleotides. Noncyclic 5 -nucleotides can be separated from cyclic 3, 5 - nucleotides, which are simultaneously present in animal, plant, and microbial tissues, by applying a nonvolatile sodium borate buffer at pH 9.3 indeed borate interacts specifically with the cis-vicinal hydroxyl groups of 5 -nucleotide ribose but not with cyclic nucleotides. 

Amino acids (0.5 mg) are dissolved in 100 )il of triethylamine-acetic acid buffer (50 ml water -f 50 ml acetone + 0,5 ml triethylamine -i- 5 ml of 0.2 M acetic acid, pH 10.65) and treated with DABITC solution (50 pi, 4 nmole/pl in acetone). The mixture is heated at 54°C for 1 h, dried under vacuum, and then redissolved in water-acetic acid (40 pi + 80 pi) saturated with HCI (alternatively, 100 pi of 50% TEA can be used instead of this aqueous acid mixture). The acid solution is heated at 54°C for 45 min and then dried again under vacuum. The dried DABTH-amino acid (about 200 nmole) is dissolved in a suitable volume of 90% ethanol and stored at -20°C for TLC analysis. The presence... 

A spectrophotometric method was worked out by Wang and coworkers [53] for the determination of trace level fluoride concentration of water samples. In this procedure, the samples are mixed with a reagent mixture (alizarin-3-methylimino-N,N-diacetic acid/ sodium acetate/12.5% acetic acid buffer of pH 4.1/1 mM lanthanum nitrate (1 1 1 )). After a reaction time the colored complex is extracted with 5% N,N-dimethylaniline solution in 3-methylbutan-l-ol and the absorbance is detected in a special, long capillary at 580 nm. 

Add 10 ml of a 01M sodium acetate-acetic acid buffer, pH 4-6. Adjust the volume to 100 ml using a mixture of equal parts of methyl cellosolve and distilled water. Add 0 2 g of lanthanum chloranilate, shake the flask immediately and then allow to stand for thirty minutes, shaking at frequent intervals. Filter or centrifuge to give a clear solution and measure the extinction in a 1-cm cell at 530 m/j, against a blank prepared in the same way. For greater sensitivity (in the range 0 5 to 4 0 jug per ml), the extinction should be measured at 330 m//. 

A mixture of acetic acid and sodium acetate is one example of an acid/base buffer. The equilibrium position of the buffer is governed by the reaction... 

Alkaline solutions of mononitroparaffins undergo many different reactions when stored for long periods, acidified, or heated. Acidification of solutions of mononitro salts is best effected slowly at 0°C or lower with weak acids or buffered acidic mixtures, such as acetic acid—urea, carbon dioxide, or hydroxyl ammonium chloride. If mineral acids are used under mild conditions, eg, dilute HCl at 0°C, decomposition yields a carbonyl compound and nitrous oxide (Nef reaction). 

The reaction of the steroidal )3-ketoaldehyde (293) with hydroxylamine hydrochloride in acetic acid gave a mixture of the 3- and 5-substituted isoxazoles (294) and (295a). In sodium acetate buffer the reaction provided exclusively the 5-substituted isomer (29Sb) (66JOC3193). 

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