Buffer solutions with dissolved sodium citrate

Sulfur Dioxide Vapor Pressure and pH of Sodium Citrate Buffer Solutions with Dissolved Sulfur Dioxide... 

Method. The stationary phase consists of the appropriate amount of picric acid dissolved in a citrate buffer system (Titrisol Merck). The pH of these solutions are checked and when necessary are adjusted to the desired pH with 5 N sodium hydroxide. The columns are packed with a slurry of silica gel by means of the equal-density procedure described earlier [54]. For other adsorbents, a new technique [55] is used for packing the slurry. After packing, twice the dead volume of chloroform is pumped through the column. The column is then heated at 180 °C for 2 h and flushed simultaneously with a gentle stream of nitrogen. The columns (usually 10 cm long) are treated with ca. 10 ml of the stationary phase at a flow-rate of 0.5 ml/min, and are then flushed with 20-40 ml of hexane. The column is equilibrated with chloroform at a flow-rate of 0.2 ml/min for various times. The samples are injected as ion pairs on to the column. Formation of the scopolamine and hyoscyamine ion pairs occurs in 5 ml of buffer solution (pH 5 or 6) to which a solution of picric acid is added containing 40 mg of picric acid in 5 ml of buffer. 

Following adjustment to pH 6.0, the solution is applied to a SP-Sephadex C-25 column in the sodium form. Amino acids are then eluted with 0.2 M citrate phosphate buffer, pH 8.0, and the effluent evaporated to dryness at 50 °C. The residue is dissolved in 0.1 N hydrochloric acid and applied to the amino acid analyser. Amino acids are separated by passing 0.2 M, pH 8 sodium citrate solution down the column. The S-methylmethionine content can then be obtained from the chromatogram, as illustrated in Fig. 8.1. The results obtained agree reasonably well with those obtained by thin-layer chromatography [13]. 

Buffer solution dissolve 4.4 g sodium chloride, NaCl, and 2.2 g sodium citrate, Na3C6H507 2H20 in 450 mL distilled water. Adjust the pH with either 0.1 M HC1 or 0.1 M NaOH to pH 7.0. Add enough water to bring to 500 mL volume. DNA solution dissolve 20 mg of calf thymus Type I highly polymerized DNA (obtainable from Sigma as well as from other companies) in 200-mL buffer solution at pH 7.0. The purchased DNA powder should be kept in the freezer. The DNA solutions should be prepared fresh or maximum 2-3 hr. in advance of the experiment. The solution should be kept at 4°C 1-2 hr. before the experiment, the solution should be allowed to come to room temperature. Label the solution as 0.01 g/dL concentration. 

Standard Solution Weigh 1250 2 mg of reagent-grade glutamic acid, and place it into a 500-mL volumetric flask. Fill the flask half-full with water, and add 5 mL of hydrochloric acid to help dissolve the amino acid, dilute to volume with water, and mix. Dilute 1 mL of this solution with 4 mL of 0.2 A sodium citrate, pH 2.2, buffer. This Standard Solution contains 0.5 mg of glutamic acid per milliliter (Cs). 

Buffer Solution Dissolve 150 g of sodium citrate dihydrate and 10.3 g of disodium EDTA dihydrate in 800 mL of water, adjust the pH to 8.0 with 50% sodium hydroxide solution, and dilute to 1000 mL with water. 

Guanidine thiocyanate solution. For 100 ml dissolve 50 g guanidine thiocyanate and 0.5 g n-lauryl sarcosine in 30 ml of sterile water. Heat and stir to help dissolution. Add 2.5 ml IM sodium citrate buffer (pH 7.0). Add 0.7 ml 6 2-mercaptoethanol. Bring the pH of the mixture to 7.0 with few drops of 0.1 N NaOH. Bring up to 100 ml with sterile distilled water. Filter the solution on a millipore filter. Do not keep more than 2 weeks. Cesimn chloride solution dissolve 63 g CsCl in 49 ml water and add 1.25 ml 1 m NaAc(pH5.0). 

Meclofenamic acid from plasma and citrate buffer solution (pH 4.6) containing diclofenac sodium (IS) were mixed with CH2CI2 the mixture is centrifuged, the organic phase is evaporated to dryness, and the residue is dissolved in the mobile phase Linearity 0.20-4.8 p,g/ml meclofenamic acid Linearity 50-500% of the expected working assay of tolfenamic acid and RSD were <1% ... 

Benzoic acid To a suitable volume of sample add 20 ml of buffer solution (10 per cent sodium citrate and 6-5 per cent citric acid adjusted to pH 4-0) and extract three times with 25 ml of ether, washing each extract with a few millilitres of water and reserving the washings. Filter through a dry paper, remove the ether at a low temperature, the last few millilitres at room temperature. To the residue add 3 ml of pure acetone and remove cautiously. Dissolve the residue in a further 2 ml of acetone,... 

Reagent Thiobarbituric acid solution. Dissolve 5 g of 2-thiobarbituric acid in 20 ml of N sodium hydroxide diluted with 500 ml of water. Add 250 ml of citrate buffer solution (prepared by dissolving 37 g of sodium citrate dihydrate in water, adding 32 ml of concentrated hydrochloric acid and diluting to 250 ml with water) and adjust the pH to 2 0. Store in glass-stoppered bottles in a refrigerator. 

Buffer Solution. dH = 5.2 - Dissolve 33 g potassium sodium tartrate, C,HP5KNa.4HjO, in a 1000-mL volumetric flask, which already contains about 800 ml water. Add 24 g sodium citrate, CjHPjNa3.2H20 and dissolve. Make up to volume and check the pH and correct if necessary with HCI to 5.2 0.1. Add 3 ml Brij 35 (30 %) (Sigma Chemical Co. nr 430AG-6) and mix. 

Citrate-acetate buffer. 20 mM citric acid, O.lAf sodium acetate, 0 1 mM Na2EDTA, 0 1 mM octanesulfonate, 1 mM dibutylamine, pH 4 2 To prepare 1 L Dissolve 37.2 mg Na2EDTA (dihydrate) with about 50 mL purified water, then add 13.6 g of sodium acetate (trihydrate), 4.2 g of citric acid (monohydrate), 21.6 mg of octanesulfonate, and 170 pL of dibutylamine and dilute with purified water to 1 L. Adjust the pH of this solution to 4.2 with concentrated phosphoric acid and filter through a 0,2-pm membrane. This solution can be kept at 4 C for up to 3 wk. 

Substrate Solution. 4 volumes of an aqueous solution of purified hyaluronate are mixed with 1 volume of Mcllvaine (109) citrate-phosphate buffer, pH 7.0, containing sodium chloride. The buffer is prepared by dissolving 12.75 g. of anhydrous disodium phosphate, 2.02 g. of citric acid, and 3.50 g. of sodium chloride per liter. After dilution, it is Af/60 (0.017 M) with respect to phosphate and contains 0.012 M sodium chloride. The concentration of the substrate is chosen to give a relative viscosity of 3 to 4. 

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