Magnesium ammonium orthophosphate

In most analytical procedures for determining the total phosphoms content (normally expressed in terms of P20 ), the phosphates are converted to the orthophosphate form. Typically, condensed phosphates are hydrolyzed to orthophosphate by boiling in dilute mineral acid (0.1 N). The orthophosphate is then deterrnined by gravimetric or spectrophotometric methods. For gravimetric deterrnination, insoluble phosphomolybdates (or magnesium ammonium orthophosphate) is formed. 

Phosphate. Because of interference by uranium in the usual magnesium ammonium orthophosphate procedure,5 uranium is first removed by a cation-exchange procedure. A column (2.5 by 36 cm.) of 50 to 75 cc. of Dowex-50 resin is washed with 200 ml. of Z N hydrochloric acid and then 200 ml. of water at flow rates of 2 to 3 ml./min. An acidic solution of the product, containing 100 to 150 mg. of orthophosphate, is passed through the column at a rate of 1 ml./min. The column is washed with water until the washings are neutral to litmus, and phosphate is determined in the combined eluate and washings by the usual gravimetric procedure.6 Uranium can be eluted from the... 

Synonyms magnesium ammonium orthophosphate Magnesium Carbonate... 

Magnesium Aluminum Silicate BC 1(H)] Magnesium Aluminum Silicate BC 101] Magnesium Aluminum Silicate BC 102] Magnesium Aluminum Silicate BC 103. See Magnesium aluminum silicate Magnesium ammonium orthophosphate. See Magnesium ammonium phosphate, hexahydrate... 

The principal reaction product in the system based on magnesia and ammonium dihydrogen orthophosphate is magnesium ammonium phosphate hexahydrate (struvite) ... 

Magnesium orthophosphate Mg3(P04)2 constitutes rhombic crystals melts at 1,184°C insoluble in water soluble in ammonium salt solution. 

Orthophosphate, (i) Ammonium molybdate test (temperature not above 40°) (IV.28, 4). (ii) Magnesium nitrate reagent test (IV.28, 3). 

Mono- and diammonium phosphate are used as solid fertilizers, whereas ammonium polyphosphate is mainly utilized in solution as a liquid fertilizer, since unlike the orthophosphates, it is very soluble and is more difficult to granulate than the orthophosphates. As a result of its complexing properties, it also keeps impurities (iron, aluminum, magnesium etc.) in solution. 

To 1 to 1 5 g of syrup in a covered platinum dish add 0 5 g of light magnesium oxide, take to dryness on a water-bath and carefully ignite. Heat the white ash obtained for thirty minutes in the presence of 5 per cent nitric acid to ensure the whole of the phosphate being present as orthophosphate. Proceed by the method given on p. 530, but using 15 g of ammonium nitrate in precipitation and allowing the precipitated phosphomolybdate to stand for one hour before filtration. 

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