Buffer solutions dilute buffers

Buffer solution, dilute. To one volume of concentrated buffer solution, add five volumes water and adjust the pH to 6.1 by adding acetic acid or sodium hydroxide solution. 

Procedure. Transfer the neutral sample solution (<100 gMg), free from calcium and other metals, to a 100 mL graduated flask with calibrated neck. Add 25 mL of the buffer solution, dilute to just below the 90 mL graduation mark, and shake. Add 10.0 mL of the solochrome black solution carefully. Shake to mix and dilute to the 100 mL mark with water. Measure the absorbance immediately at 520 nm (green filter) against that of a blank solution, similarly prepared but containing no magnesium. 

P 82] Dilution-type mixing was accomplished with the fluorescent dyes acridine orange (0.01% solution in 20 mM in TE buffer see below) or trypan blue (prepared in 0.85% saline) contacted with buffer solution (TE buffer 10 mmol f4 Tris-HCl, pH 7.4, 1 mmol 1 1 EDTA, pH 8.0) [164]. Images were taken by a laser scanning confocal microscope. Profiling data analysis was employed along detection lines. 

Standard Solution Dissolve an accurately weighed quantity of USP Sodium Fluoride RS quantitatively in water to obtain a solution containing 1.1052 mg/mL. Transfer 20.0 mL of the resulting solution into a 100-mL volumetric flask containing 50 mL of Buffer Solution, dilute to volume with water, and mix. Each milliliter of this solution contains 100 p,g of fluoride ion. 

Standard Preparation Use a commercial reference standard lysozyme of a specified strength from an animal or microbial source in accordance with the origin of the preparation being measured. Measure 50 mg of the reference standard lysozyme into a 50-mL volumetric flask, and dissolve, with stirring, in approximately 25-mL of Sodium Phosphate Buffer Solution. Dilute to volume with Sodium Phosphate Buffer Solution, and mix thoroughly. If desired, freeze aliquots of this Standard Preparation for subsequent assays. Quantitatively transfer 3 mL of the Standard Preparation to a 100-mL volumetric flask, and dilute to volume with Sodium Phosphate Buffer Solution. 

Our initial studies using the kits were disappointing, invariably resulting in modifications of the kits themselves and changes in protocols for use of the kits. Following this initial phase of work, we decided one kit was ready for collaborative study. This first collaborative study involved use of the Neogen Agri-Screen kit. The antibodies have specific ability to bind aflatoxin B, and very low cross reactivity to aflatoxins B, G, and G,. This kit contains Antibody-coated microtiter wells Aflatoxin standard solution Dilution buffer (Tris)... 

Add 6 M HCl (previously boiled and cooled) to the sample solution, containing not more than 60 pg of Te, until the concentration of HCl is 3 M. Add 4 ml of Bismuthiol II solution, and stir thoroughly. After 1 min, extract Te by shaking with two 10-ml portions of chloroform for 1 min. Wash the extract with the buffer solution. Dilute the extract to the mark with chloroform in a 25-ml standard flask. Measure the absorbance of the yellow solution at 330 nm, using a reagent blank solution as reference. 

Dissolve 0.016 g of pinacyanol in exactly 500 ml of buffer solution, dilute to 2000 ml with distilled water, and filter. Keep this solution in the dark in a glass bottle. The solution should be renewed every 2-3 weeks and should have a pH in the range 8.4-8.6. 

The working conditions of the immunosensor (enzyme and antigen concentrations, dilutions of the antibodies, pH of the buffer solution) were found. The cholinesterase immobilized demonstrated the maximum catalytic activity in phosphate buffer solution with pH 8.0. The analytical chai acteristics of the sensor - the interval of the working concentrations and detection limit - have been obtained. The proposed approach of immunoassay made possible to detect 5T0 mg/ml of the bacterial antigen. 

An amount of enzyme preparation equivalent to 900 mg of wet cells was made up to 25 ml with the above potassium phosphate buffer solution. 150 mg (1.15 mmol) of 5-fluorouracil and 1.0 gram of thymidine (4.12 mmol) were dissolved in 15 ml of the above potassium phosphate buffer solution. The mixture was incubated at 37°C for 18 hours. After this time, enzyme action was stopped by the addition of four volumes of acetone and one volume of peroxide-free diethyl ether. The precipitated solids were removed by filtration, and the filtrate was evaporated under nitrogen at reduced pressure until substantially all volatile organic solvent had been removed. About 20 ml of aqueous solution, essentially free of organic solvent, remained. This solution was diluted to 100 ml with distilled water. 

Calcium Chloride [25]. Calcium chloride estimation is based on calcium titration. To 20 ml of 1 1 mixture of toluene (xylene) isopropyl alcohol, add a 1-ml (or 0.1-ml, if calcium is high) sample of oil-base mud, while stirring. Dilute the mixture with 75 to 100 ml of distilled water. Add 2 ml of hardness buffer solution and 10 to 15 drops of hardness indicator solution. Titrate mixture with standard versenate solution until the color changes from wine-red to blue. If common standard versenate solution (1 ml = 20 g calcium ions) is used, then... 

Before leaving the subject of buffer solutions, it is necessary to draw attention to a possible erroneous deduction from equation (21), namely that the hydrogen-ion concentration of a buffer solution is dependent only upon the ratio of the concentrations of acid and salt and upon Ka, and not upon the actual concentrations otherwise expressed, that the pH of such a buffer mixture should not change upon dilution with water. This is approximately although not strictly true. In deducing equation (18), concentrations have been substituted for activities, a step which is not entirely justifiable except in dilute solutions. The exact expression controlling buffer action is ... 

If a buffer solution is diluted, the ionic concentrations are decreased and so, as shown in Section 2.5, the ionic activity coefficients are increased. It follows from equation (26) that the pH is increased. 

Buffer solution, pH = 10. Dissolve 7.0 g of analytical grade ammonium chloride and 57 mL of concentrated ammonia solution (sp. gr. 0.88) in water and dilute to 100 mL. 

Analyses, (a) Original zinc-ion solution. Dilute 2.00 mL (pipette) to 100 mL in a graduated flask. Pipette 10.0 mL of the diluted solution into a 250 mL conical flask, add ca 90 mL of water, 2 mL of the buffer solution, and sufficient of the solochrome black indicator mixture to impart a pronounced red colour to the solution. Titrate with standard 0.01 M EDTA to a pure blue colour (see Section 10.59). 

In some of the details which follow, reference is made to the addition of a buffer solution, and in all such cases, to ensure that the requisite buffering action is in fact achieved, it is necessary to make certain that the original solution has first been made almost neutral by the cautious addition of sodium hydroxide or ammonium hydroxide, or of dilute acid, before adding the buffer solution. When an acid solution containing a metallic ion is neutralised by the addition of alkali care must be taken to ensure that the metal hydroxide is not precipitated. 

Procedure. Prepare an ammonia-ammonium chloride buffer solution (pH 10), by adding 142 mL concentrated ammonia solution (sp. gr. 0.88-0.90) to 17.5 g ammonium chloride and diluting to 250 mL with de-ionised water. 

Pipette 25.0 mL of the 0.01 M calcium ion solution into a 250mL conical flask, dilute it with about 25 mL of distilled water, add 2mL buffer, solution, 1 mL 0.1M Mg-EDTA, and 30-40mg solochrome black/potassium nitrate mixture. Titrate with the EDTA solution until the colour changes from wine red to clear blue. No tinge of reddish hue should remain at the equivalence point. Titrate slowly near the end point. 

Pipette 25 mL hickel solution (0.01 M) into a conical flask and dilute to 150 mL with de-ionised water. Add about 15 drops of the indicator solution, 10 mL of the buffer solution and titrate with standard EDTA solution (0.01 M) until the colour changes from blue to claret red. 

Buffer solution. Add 55 mL of concentrated hydrochloric acid to 400 mL de-ionised water and mix thoroughly. Slowly pour 310 mL of redistilled monoethanolamine with stirring into the mixture and cool to room temperature (Note 2). Titrate 50.0 mL of the standard magnesium chloride solution with standard (0.01M) EDTA solution using 1 mL of the monoethanolamine-hydrochloric acid solution as the buffer and solochrome black as the indicator. Add 50.0 mL of the magnesium chloride solution to the volume of EDTA solution required to complex the magnesium exactly (as determined in the last titration), pour the mixture into the monoethanolamine-hydrochloric acid solution, and mix well. Dilute to 1 litre (Note 3). 

Procedure. Prepare an EGTA solution (0.05M) by dissolving 19.01 g in 100 mL sodium hydroxide solution (1M) and diluting to 1 L in a graduated flask with de-ionised water. Prepare the indicator by dissolving 0.065 g zincon in 2 mL sodium hydroxide solution (0.1M) and diluting to 100 mL with de-ionised water, and a buffer solution (pH 10) by dissolving 25 g sodium tetraborate, 3.5 g ammonium chloride, and 5.7 g sodium hydroxide in 1 L of de-ionised water. 

Pipette 25 mL of the solution containing magnesium, manganese and zinc ions (each approx. 0.02M), into a 250 mL conical flask and dilute to 100 mL with de-ionised water. Add 0.25 g hydroxylammonium chloride [this is to prevent oxidation of Mn(II) ions], followed by 10 mL of the buffer solution and 30-40 mg of the indicator/potassium nitrate mixture. Warm to 40 °C and titrate (preferably stirring magnetically) with the standard EDTA solution to a pure blue colour. 

Ammonia buffer solution. Mix 20 g ammonium nitrate and 35 mL concentrated ammonia solution, and make up to 100 mL with distilled water. Dilute 80 mL to 1 L with distilled water. The pH is about 10.1. 

When the electrode is placed in an aqueous solution of glucose which has been suitably diluted with a phosphate buffer solution (pH 7.3), solution passes through the outer membrane into the enzyme where hydroxen peroxide is produced. Hydrogen peroxide can diffuse through the inner membrane which, however, is impermeable to other components of the solution. The electrode vessel contains phosphate buffer, a platinum wire and a silver wire which act as electrodes. A potential of 0.7 volts is applied to the electrodes (the apparatus shown in Fig. 16.17 is suitable) with the platinum wire as anode. At this electrode the reaction H202->02 + 2H+ +2e takes place, and the oxygen produced is reduced at the silver cathode ... 

The poor solubility of coelenterazine in neutral aqueous buffer solutions often hampers the use of this compound in biological applications. The simplest way to make an aqueous solution is the dilution of a methanolic 3 mM coelenterazine with a large volume of a desired aqueous buffer solution. If the use of alcoholic solvents is not permitted, dissolve coelenterazine in a small amount of water with the help of a trace amount of 1 M NaOH or NH4OH, and then immediately dilute this solution with a desired aqueous buffer solution. However, because of the rapid oxidation of coelenterazine in alkaline solutions, it is recommended that the procedure be carried out under argon gas and as quickly as possible. 

Sometimes an aqueous extract of a luminous organism is nonlu-minous although it contains all the components necessary for light emission. If that is due to the presence of various inhibitors that are extracted together with the luminescent substances, the extract will become luminous by merely diluting the extract with water or a buffer solution. A means of reversible inhibition will be needed to purify such a luminous extract. 

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