Magnesium pyrophosphate

Phosphites, D. of as ammonium magnesium phosphate or as magnesium pyrophosphate, (g) 497 as mercury(I) chloride by mercury(II) chloride, (g) 486 Phosphorescence 731... 

Handschuh and Orgel (1973) studied the mineral struvite. It can be precipitated from ocean water in the presence of phosphate if the concentration of NH ions in the water is greater than 0.01 M. If struvite is heated with urea, magnesium pyrophosphate is obtained in a yield of about 20% after 10 days at 338 K if nucleosides are added to the reaction mixture described above, nucleoside diphosphates such as uridine-5 -diphosphate and diuridine-5 -diphosphate are formed in good yields. 

Phosphorus is a common component of additives and appears most commonly as a zinc dialkyl dithiophosphate or triaryl phosphate ester, but other forms also occur. Two wet chemical methods are available, one of which (ASTM D1091) describes an oxidation procedure that converts phosphorus to aqueous orthophosphate anion. This is then determined by mass as magnesium pyrophosphate or photochemically as molybdivanadophosphoric acid. In an alternative test (ASTM D4047), samples are oxidized to phosphate with zinc oxide, dissolved in acid, precipitated as quinoline phosphomolybdate, treated with excess standard alkali, and back-titrated with standard acid. Both of these methods are used primarily for referee samples. Phosphorus is most commonly determined using x-ray fluorescence (ASTM D4927) or ICP (ASTM D4951). 

For a reaction in which the stoichiometric relation between analyte and product is not 1 1, we must use the correct stoichiometry in formulating the gravimetric factor. For example, an unknown containing Mg2+ (atomic mass = 24.305 0) can be analyzed gravimetrically to produce magnesium pyrophosphate (Mg2P207. FM 222.553). The gravimetric factor would be... 

Pyrophosphatases, which are present in all cells, and catalyze hydrolysis of inorganic pyrophosphate (PPj) to orthophosphate (P ) (see Chapter 6, Section D), also drive metabolic sequences. The very active pyrophosphatase of E. coli has a turnover number of over 2 x 104 s 1 at 37°C. The 1000 molecules per cell are sufficient to immediately hydrolyze any pyrophosphate produced by bacterial metabolism.733 The much studied soluble pyrophosphatases of E. coli,7 A 7 ,r yeast,736 and other organisms736ab are metalloenzymes that are most active with Mg2+. Two Mg2+ ions are held, mostly by carboxylate side chains, while a third apparently enters the active site as magnesium pyrophosphate, perhaps MgP20-. As with other metallohydrolases, a metal-bound hydroxyl ion may serve as the attacking nucleophile. 

Magnesium Ammonium Phosphate. MgNH(POr. white precipitate. K,t, 2.5 x 0 1 -. by reaction of soluble salt solution and sodium phosphate in the presence of excess ammonium hydroxide, upon igniting yields magnesium pyrophosphate. MgyPsOz. while solid. 

In an aliquot part of this solution (100 or 150 c.c.) the phosphoric acid is determined either by the ammonium molybdate method or as magnesium pyrophosphate (see Vol. I, p. 132). 

As Magnesium Pyrophosphate. The organic matter of the wine is oxidised by means of nitric acid and the phosphorus then estimated as magnesium pyrophosphate. 

Incubate the transcription solution for 5 h at 40°C. White precipitant is due to magnesium pyrophosphate after the reaction (see Note 3). 

Phosphorus may be determined gravimetrically as magnesium pyrophosphate after oxidation of the phosphite to phosphate by bromine and nitric acid. A sample is hydrolyzed in sodium hydroxide solution and diluted to 500 ml. in a volumetric flask. The analyses are run with 50-ml. aliquots. Each aliquot is acidified with 5 ml. of concentrated, 16 M nitric acid, and M nil. (5 drops) of bromine is added (a slight excess over the amount required for complete oxidation of an aliquot containing 0.2 g. of methyl ehlorofluorophosphite). The solution is swirled for a few seconds and allowed to stand for 15 minutes, with swirling at intervals. It is then heated on a steam cone until the color of the bromine disappears (the volume is usually reduced considerably during this process). The solution is... 

Magnesium Phosphate, Dibasic, Mixed Hydrates, occurs as a white, crystalline powder that is a partially dehydrated form of a mixture of magnesium phosphate, dibasic—in the trihydrate, dihydrate, and anhydrous forms—and of magnesium pyrophosphate. It is slightly soluble in water and insoluble in alcohol, but is soluble in dilute acids. 

La2H18021S3 lanthanum sulfate nonahydrate 10294-62-9 25.00 2.8200 1 2448 Mg2H6O10P2 magnesium pyrophosphate trihydrate 10102-34-8 25.00 2.5600 1... 

Another example is in the separation of sulfate or phosphate from various cations. Samuelson devised a method for sulfur in pyrites that is based on the retention of iron(m) on a cation-exchange resin. The sulfuric add that passes through the colunm can be determined by the usual gravimetric method as barium sulfate. In a similar way, phosphate in phosphate rock can be determined by retention of calcium, magnesium, iron, and aluminum on a cation-exchange resin followed by deterlnination of the phosphate as magnesium pyrophosphate. The metal ions can be eluted from the column with 4 M hydrochloric acid. 

Properties White powder. D 1.71, mp (decomposes to magnesium pyrophosphate, Mg2P207). Soluble in acids insoluble in alcohol and water. 

Other kinetic studies of complexation using relaxation techniques can be found in Bridger et al. (1983) [hydroxo and chloro complexes of Fe(III)], Bridger et al. (1982) [complexation of Fe(III) by picolinic and dipicolinic acids], Strahm et al. (1979) (complexation of aqueous iron chloride), and Patel and Taylor (1973) (complexation of magnesium pyrophosphates). 

Phosphorus can serve as a benehcial adjunct or as a deleterious agent. There are several test methods for the determination of phosphorus. In addition to the three test methods described here, reference should also be made to multielement analysis methods such as inductively coupled plasma atomic emission spectroscopy (ICPAES) (ASTM D-4951, ASTM D-5185) and X-ray fluorescence (XRF) (ASTM D-4927, ASTM D-6443) described above in this guide. Phosphorus can also be determined by a photometric procedure (IP 148) or by a test method (ASTM D-1091) in which the organic material in the sample is destroyed, phosphorus in the sample is converted to phosphate ion by oxidation with sulfuric acid, nitric acid, and hydrogen peroxide, and the magnesium pyrophosphate is determined gravimetrically. Another method (ASTM D-4047, IP 149) in which the phosphorus is converted to quinoline phosphomolybdate is also available. 

It is not known whether magnesium pyrophosphate and the 3 -hydroxyl group of a nick in DNA share a common acceptor binding site of DNA ligase, in analogy to the acceptors in reactions (35a), (36a), and (37a) discussed above. It seems unlikely that a limited binding site could acconunodate such diverse ac-... 

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