Potassium phosphate, solution preparation

Standard Phosphate Solution Prepare a 9.0-mM phosphate stock solution. Dissolve and dilute 612.4 mg of potassium dihydrogen phosphate (KH2P04) (dried in desiccator with silica) to 500 mL with water in a volumetric flask. Make the following dilutions in water from the stock solution, and use these as standards. 

In addition to using blends of tetracalcium and dicalcium phosphate for preparing suspensions that set and harden with time, such blends may also be used for producing compacts that may attain high strengths if placed into appropriate solutions. Flexural strengths of up to 28 MPa have been reported in compacts stored in a saturated potassium phosphate solution (Vanis and Odler, 1997). 

Nature of the Suppression Effect of Caraway Seed. Since analytical data demonstrated that the addition of caraway seeds depleted volatile sulfur compounds in sauerkraut, this effect was studied using aqueous extracts of caraway seeds and authentic volatile sulfur compounds in model systems. Cell-free crude caraway seed extracts were prepared by blending the unheated spice seeds with chilled (ice water) potassium phosphate solutions (50 mM, pH 7) containing 0.1 M potassium chloride (1 5, w/w) in a cold room (4°C). Homogenates were then clarified by filtration and centrifugation as described by Chin (21). Data in Figure 7 shows that unheated and heat-treated crude caraway seed extracts (1 mL in a 3 mL buffered solution, pH 8) removed methanethiol (10 pg) from the headsapce in closed serum-type vials (120 mL) at 37 which indicated that both heat-stable and heat-labile entities in caraway seed were involved in the depletion of methanethiol. 

The U.S.P. method for stilboestrol which is more specific than the above is based on a method proposed by Goodyear, Hatfield and Marsh. 25 ml of a solution of the sample in 95 per cent ethanol, prepared to contain about 20 /jig per ml, is mixed with an equal volume of dibasic potassium phosphate solution (1 in 55) and the solution, in a quartz cell or tube, is then irradiated in ultra-violet light and its extinction measured at the maximum at about 418 m, when the maximum yellow colour has been developed. The optimum conditions (time of irradiation, distance from source of light and quality of quartz container) for maximum colour development are determined prior to making the determination, using a standard solution of stilboestrol in 95 per cent ethanol, containing 20 /ug per ml, and the stilboestrol content of the sample is determined from a comparison of the extinction of the sample solution with that of the standard solution determined at the same time under these conditions. This method has been adapted by the Analytical Methods Committee of the S.A.C. for determination of small amounts of stilboestrol (about 5 mg per pound) in complex mixtures such as animal feeding-stuffs. 

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. 

Gotti et al. [42] reported an analytical study of penicillamine in pharmaceuticals by capillary zone electrophoresis. Dispersions of the drug (0.4 mg/mL for the determination of (/q-penicillaminc in water containing 0.03% of the internal standard, S -met hy I - r-cystei ne, were injected at 5 kPa for 10 seconds into the capillary (48.5 cm x 50 pm i.d., 40 cm to detector). Electrophoresis was carried out at 15 °C and 30 kV, with a pH 2.5 buffer of 50 mM potassium phosphate and detection at 200 rnn. Calibration graphs were linear for 0.2-0.6 pg/mL (detection limit = 90 pM). For a more sensitive determination of penicillamine, or for the separation of its enantiomers, a derivative was prepared. Solutions (0.5 mL, final concentration 20 pg/mL) in 10 mM phosphate buffer (pH 8) were mixed with 1 mL of methanolic 0.015% 1,1 -[ethylidenebis-(sulfonyl)]bis-benzene and, after 2 min, with 0.5 mL of pH 2.5 phosphate buffer. An internal standard (0.03% tryptophan, 0.15 mL) was added and aliquots were injected. With the same pH 2.5 buffer and detection at 220 nm, calibration graphs were linear for 9.3-37.2 pg/mL, with a detection limit of 2.5 pM. For the determination of small amounts of (L)-penicillamine impurity, the final analyte concentration was 75 pg/mL, the pH 2.5 buffer contained 5 mM beta-cyclodextrin and 30 mM (+)-camphor-10-sulfonic acid, with a voltage of 20 kV, and detection at 220 nm. Calibration graphs were linear for 0.5-2% of the toxic (L)-enantiomer, with a detection limit of 0.3%. 

The solution is prepared by dissolving 22.3 g (105 mmol) of potassium phosphate (Nakarai Chemicals, Japan) in water and adjusting the final volume to 35 mL. The original method5 used sodium hydroxide as base potassium phosphate is desirable for the extension of the present procedure to base-sensitive compounds. Under such conditions, the reaction with 9-(10-carbomethoxydecanyl)-9-BBN proceeds similarly without saponification of the ester group. 

Prepare a solution of 5 m 3-cyanopyridine (320 mL) to be used as substrate for nicotinic acid preparation in 0.1 m potassium phosphate buffer pH 8.0. 

Stock solution 5. 1 m stock solution of potassium phosphate buffer was prepared by dissolving K2HP04-3H20 (11.423 g) and KH2PO4 (6.805 g) in deionized water to a final volume of 100 mL. The pH was adjusted to 7.0. This 1 m stock solution was diluted to the desired concentration of 50 mM with deionized water. Buffers were stored at 0-4 °C. 

G.15 A chemist prepared an aqueous solution by mixing 2.50 g of ammonium phosphate trihydrate, (NH4)3P04-3H20 and 1.50 g of potassium phosphate, K3P04, with 500 g of water, (a) Determine the number of moles of formula units of each compound that was measured, (b) How many moles of P043- are present in solution (c) Calculate the mass of phosphate ions present in the solution, (d) What is the total mass of the water present in the solution ... 

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. 

This compound is determined using HPLC analysis. A Diluent reagent is prepared as a 9 1 mixture of water and methanol. The Mobile Phase is prepared as a filtered and degassed solution by dissolving 5.6 g of monobasic potassium phosphate in 820 mL of water in a 1-liter volumetric flask, adjusting with phosphoric acid to a pH of 4.3, diluting with methanol to volume, and mixing. Adjustments in the composition may be made if required by the System Suitability requirements. 

Mild acidification of molybdate-phosphate solutions yielded the colorless [P2Mos023]"6 anion, isolated as the sodium salt48,49 The heteropoly acid containing pentavalent antimony, H3[SbMo12O40] 48 H20, was reported to have been prepared by refluxing M/20 molybdic acid with M/75 potassium pyroantimonates°), however, more work is necessary to elucidate to exact nature of molybdenum heteropoly compounds containing antimony. 

A. faecalis azurin. The apoprotein was prepared as described under Experimental Solutions 9 X 10 5 M in 0.1 M potassium phosphate, pH 7.0. Optical pathlength, 10 mm. 

After preincubation of the brush border membrane vesicle preparation for 2 h, [2 14 C]urate uptake is initiated by adding 200 pi of incubation medium to 20 pi of the membrane suspension. The incubation medium has the following composition (mmol/1) 150 mannitol, 2 MgS04, 50 potassium phosphate buffer, pH 6.0 or 7.5, 0.02 [2-14 C]urate, and various concentrations of the inhibitor. At 10 s after the addition of the incubation medium, 200 pi portions of the suspension are pipetted onto the center of prewetted cellulose acetate filters kept under suction. The vesicles retaining on the filter are washed immediately with 5 ml of an ice-cold solution containing 150 mmol/1 mannitol and 50 mmol/1 potassium phosphate buffer, pH 6.0 or 7.5, which is used at the same pH as the incubation medium. Preincubations and incubations are performed at 23 1 °C. Each experiment is performed in triplicate. Corrections are made for the radioactivity bound to the filters in the absence of membrane vesicles. The term of the OH gradient-dependent urate uptake is defined as the difference between the uptakes in the incubation medium at pH 6.0 and that at pH 7.5. The OII gradient-dependent urate uptake at 10 s is assumed to present an initial velocity. 

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