Potassium dihydrogen phosphate, solution preparation

Procedure 2 (Determination of the phytase activity of the Phytase Reference Preparation) Transfer 2.00 mL of Sample Preparation, Procedure 2, and 2.00 mL (three times from Potassium Dihydrogen Phosphate Solution A and two times from B) of Potassium Dihydrogen Phosphate Solutions into separate 20- x 150-mm glass test tubes. Using a stopwatch and starting at time equals zero, in the order of the series and within regular time intervals, place the tubes into a 37.0° 0.1° water bath and allow their contents to equilibrate for 5 min. At time equals 5 min, in the same order of the series and within the same time intervals, add 4.0 mL of Substrate Solution (previously equilibrated to 37.0° 0.1°) to the test tubes. Mix, and replace in the 37.0° 0.1° water bath. At time equals 35 min, in the same order and within the same time intervals, terminate the incubation by adding 4.0 mL of Color/Stop Solution. Mix, and cool to ambient temperature. 

Calculation, Procedure 2 Calculate the corrected absorbances Ar for each Sample Preparation (absorbance Phytase Reference Solution minus corresponding absorbance blank) and for each Potassium Dihydrogen Phosphate Solution, Ap (absorbance Potassium Dihydrogen Phosphate Solution minus average absorbance reagent blank). Calculate C, the phosphate concentration of each Potassium Dihydrogen Phosphate Solution ... 

A standard solution containing 40 mg P F1 prepared by dissolving potassium dihydrogen phosphate (0.1757 g) in about 900 ml water and adjusting to 11. This solution is then diluted to give standards of 5,10,25,50,75,100 pg P H, and water blanks are also prepared. 

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. 

Potassium diammonium phosphate, K(NH4)2P04,4H20, is obtained by passing ammonia into a cooled solution of potassium dihydrogen phosphate, and filtering rapidly in an atmosphere of ammonia. On exposure to air, the deliquescent salt evolves ammonia, but it can be preserved in sealed tubes.3 Other double salts with sodium,4 and with lithium6 and potassium,6 have been prepared. 

Each buffer system is generally applicable over a limited range, viz., about 2 units of pH, but by making suitable mixtures of acids and acid salts, whose pfca values differ from one another by 2 units or less, it is possible to prepare a universal buffer mixture by adding a pre-deter-mined amount of alkali, a buffer solution of any desired pll from 2 to 12 can be obtained. An example of this type of mixture is a system of citric acid, diethylbarbituric acid (veronal), boric acid and potassium dihydrogen phosphate this is virtually a system of seven acids whose exponents are given below. 

Standard Solutions Standard solutions in the range 0-40 ppm P-PO4 is prepared by successive dilutions of a 100 ppm phosphate stock solution (0.4390 g of anhydrous potassium dihydrogen phosphate per liter). 

Heavy metal orthophosphates (M = Cr, Mn, Fe, Co, Ni, Zn, Hg, Pb, Ag) can be prepared in hydrated form by simple double decomposition involving aqueous solutions of an alkali hydrogen phosphate and the appropriate metal salt. Cobalt phosphate octahydrate, for example, is obtainable as a beautiful lavender-coloured precipitate from cobalt chloride and potassium dihydrogen phosphate. 

Reaction buffers were prepared by adding 4 volumes of 10 mM aqueous potassium dihydrogen phosphate odium hydroxide buffer (pH 6.S-7.6) to 6 volumes of dimethyl sulfoxide. The resulting solutions had pHs ranging from 10.6 to 11.5 as determined with the glass electrode. -Cyclodextrin solutions (0.9-6.0 mM) were prepared with this buffer and stored under nitrogen. Substrate solutions (3-4 mM in dimethyl sulfoxide) were stored in the dark. 

Preparation 24 g anhydrous disodium-hydrogen-phosphate (Na2HP04) and 46 g anhydrous potassium-dihydrogen-phosphate (KH2PO4) are dissolved in distilled water. To this, 100 cm 0.02 M EDTA solution and 0.020 g mercury(II) chloride (HgClj) are added and the volume filled up to 1000 cm. ... 

A chemist needs a 500.0 mL of a 0.35 M solution of potassium dihydrogen phosphate (KH2PO4). Suppose that you are assigned to prepare this solution. You have the pure solid available, but you also have a solution that is 4.0 M. 

Stock standard phosphorus solution, dissolve 4.393 g of dried AnalaR potassium dihydrogen phosphate (KH2PO4) in 150 ml of 1 10 sulfuric acid and dilute to 1 litre with water (1.0 mg/ml phosphorus). From this prepare solutions containing 0.01 mg P/ml and 0.001 mg P/ml. 

To one of the sample solutions and one of the standard solutions add, in order, 12 ml of 5N hydrochloric acid, 15 ml of a buffer solution pH 7 5 (prepared by dissolving 178 g of dipotassium phosphate and 22 g of potassium dihydrogen phosphate in 1 litre of water), 2 ml of freshly prepared 10 per cent sodium bisulphite and 3 ml of 0 4N sodium hydroxide. Place the flasks in boiling water for exactly seven minutes and cool immediately. 

Weie h accurately an amount of powdered tablet material containing about 15 mg of riboflavine and transfer to a 250-ml graduated flask. Add about 50 ml of buffer solution pH 4-0 (prepared by diluting 250 ml of 0-2AI potassium dihydrogen phosphate and 3 6 ml of a 1 per cent v/v solution of phosphoric acid to 1 litre with water), and warm on a water-bath for fifteen minutes. Cool and make up to volume with pH 4-0 buffer solution. Dilute 25 ml of this solution to 100 ml in pH 4 0 buffer solution, filter a portion, discarding the first 20 ml and measure the maximum extinction of the clear filtrate at about 444 m/i in a 1-cm cell using pH 4 () buffer solution as the blank. Calculate the amount of riboflavine in each tablet. 

The intestinal fluid stimulant [2] consisted of a solution of pancreatin. First potassium dihydrogen phosphate (KH2PO4) (6.8 g) was dissolved in distilled water (250 ml) in a 1 litre volnmetric flask. Then 0.2 M sodium hydroxide (190 ml), sodium taurocholate (0.5 g), and distilled water (around 400 ml) were added. A solution of pancreatin (10 g, USP) was prepared separately by gradually adding the enzyme into distilled water (150 ml) to avoid the formation of lumps, and it was then transferred into the volumetric flask with gentle shaking. The pH was adjusted to 7.5 0.1 with sodium hydroxide (0.2 M), and the resulting solution was diluted to 1 litre with distilled water. 

These authors have given several procedures for the preparation of the antibiotic from cultures of M. verrucaria S 118. One liter of medium contained 20 g of glucose, 2 g of malt extract, 2 g of yeast extract, 2 g of peptone, 2 g of potassium dihydrogen phosphate, 2 g of magnesium sulfate heptahydrate and 0.2 g of ferrous sulfate heptahydrate. After 63 hours, 501 of broth was extracted with ethyl acetate, and the extract concentrated to 41. The crude product was washed with dilute sodium hydroxide solution and water and recrystalhzed to give 2.31 g of verrucarin A contaminated with small amounts of verrucarin B. Silica gel... 

---