Dissolved orthophosphate

Incubation of lake water with 32P or 33P as tracers and subsequent gel chromatography reveals that a major pathway exists between dissolved orthophosphate and the particulate phase (3, 5-7). Low-molecular-weight phosphorus forms in the presence of bacteria and algae. SUP is present in the low-molecular-weight fraction and is classified as individual DOP compounds unassociated with particulate or colloidal material. The HMW fraction found in gel chromatography studies is characterized as a colloid that contains phosphorus compounds or incorporates orthophosphate. The colloidal material then releases orthophosphate, replenishing the dissolved phosphorus cycle. In some eutrophic lakes the HMW SRP fraction can make... 

Avanzino, R.J. and V.C. Kennedy. 1993. Long-term frozen storage of stream water samples for dissolved orthophosphate, nitrate plus nitrite and ammonia analysis. Water Resour. Res. 29 3357-3362. 

In terrestrial soils and in the euphotic zone of lakes and the ocean the concentration of dissolved orthophosphate is typically low. When bioavailable phosphorus is exhausted prior to... 

Very little detail is known about the nitrogen and phosphorus cycles. Dissolved orthophosphate is taken up in plant growth and returned eventually after serving in cell fluids and tissues. It appears to be released primarily in the form of organophosphorus compounds, and at certain seasons of the year more than half the phosphorus in the water is described as "dissolved organic phosphorus. Yet as of a year or so ago... 

Phosphorus (dissolved orthophosphate plus dissolved organic phosphorus) Waste waters UV-irradiation for organic phosphorus oxidation to orthophosphate UV—Vis 0.08 mg L 1 Multi-pumping flow system vanadomolybdate method for detecting the orthophosphate [442]... 

C. Pons, I.V. Toth, A.O.S.S. Rangel, R. Forteza, V. Cerda, Multi-pumping flow system for the determination of dissolved orthophosphate and dissolved organic phosphorus in wastewater samples, Anal. Chim. Acta 572 (2006) 148. 

Phosphorus is biologically important in the form of phosphate, the most highly oxidized state of the element. The most biologically available form is dissolved orthophosphate, (P043). There are also condensed forms of phosphate, with more than one phosphorus atom per ion, such as pyrophosphate and polyphosphates. 

Phosphorus in its simplest form, dissolved orthophosphate, is taken up by photosynthetic organisms at the base of the marine food web. When phosphate is exhausted, organisms may utilize more complex forms by converting them to orthophosphate via enzymatic and microbiological reactions. In the open ocean most phosphorus associated with biogenic particles is recycled within the upper water column. 

This exercise provides an opportunity to reinforce the principles of spectrophotometry and its relationship to environmental analysis. To minimize laboratory time, the acid hydrolysis step will be eliminated and, thus, only dissolved orthophosphate will be measured. In addition to determining the phosphorus content of a surface-water sample, each student will be given an unknown sample by the instructor whose phosphorus concentration has been previously determined by anionic ion chromatography. 

The online photooxidative decomposition of phosphoms compounds to orthophosphate has also been applied to the determination of dissolved organic phosphoms (DOP) and TP in soil extracts and leachates, mnoff waters, natural, and wastewaters. For instance, the MPFS depicted in Figure 7.33 allows the spectrophotometric determination of dissolved orthophosphate and DOP in wastewater samples [106]. The determination of orthophosphate is based on the vanadomolybdate method. Inline ultraviolet photooxidation is employed to mineralize organic phosphoms to orthophosphate prior to detection. A solenoid valve allows the deviation of the flow toward the UV lamp to carry out the determination of organic phosphoms. 

MPFS system for the spectrophotometric determination of dissolved orthophosphate and dissolved organic phosphorus in wastewater samples. MP solenoid micropump RC reaction coil. 

The solubihty of a number of sodium orthophosphates is depicted in Figure 7. Some of the sodium phosphates dissolve or precipitate incongmendy, affording a different Na20/P20 ratio in the solution phase from that of the soHd phase. Sodium phosphates that precipitate are also a function of the temperature. As the temperature increases, the sodium phosphates that may precipitate from solution tend to be anhydrous or lower hydrates than those equiUbrium sodium phosphate phases at lower temperature. Whereas most of the phases in Figure 7 represent congmentiy soluble sodium phosphates, soHd phases appear or disappear upon changes in temperature. 

As described in U.S. Patent 2,929,763, methandrostenolone may be made by a fermentation route. 2 g of sodium nitrate, 1 g of primary potassium orthophosphate, 0.5 g of magnesium sulfate heptahydrate, 0.5 g of potassium chloride, 50 g of glucose and 1 g of Difco yeast extract are dissolved in one liter of tap water, brought to pH 5 by addition of a sodium hydroxide solution and sterilized. The resulting nutrient solution is inoculated with 50 cc of a 4-day-old shaking culture of Didyniel/a lycopersici and shaken for 48 hours at 27 C, whereby the culture becomes well developed. 

Solubilizing activity are also used in enhanced oil recovery. Tar and extremely viscous hydrocarbons are recovered by the injection of an aqueous solution of an anionic orthophosphate ester surfactant into a petroleum formation, retaining the surfactant in the formation for about 24 h, and displacing the solubilized hydrocarbons toward a recovery well. The surfactant forms an oil microemulsion with the hydrocarbons in the formation. An anionic monoorthophosphate ester surfactant which is a free acid of an organic phosphate ester was dissolved in water. The input of surfactant solution was 2-25% of the pore volume of the formation [250]. To produce a concentrate for the manufacture... 

When cyanoacetylene (5), which is produced when an electric discharge is passed through a mixture of methane and nitrogen, is dissolved in a phosphate buffer a stable enol-phosphate (6) is formed. Pyrophosphate is produced when neutral aqueous solutions of (6) and orthophosphate are heated, and the phosphorylation of UMP has been achieved. However, from a study of the rate of phosphorylation and a consideration of environmental factors, especially the likely phosphate concentration in oceans, it is suggested that (6) is not an important intermediate in prebiotic phosphorylation. The conversion of the 3 -phosphate of 0 2 -cyclocytidine (7) into 2, 3 -cyclic CMP under mild conditions in aqueous solution has... 

Eberlein and Kattner [194] described an automated method for the determination of orthophosphate and total dissolved phosphorus in the marine environment. Separate aliquots of filtered seawater samples were used for the determination orthophosphate and total dissolved phosphorus in the concentration range 0.01-5 xg/l phosphorus. The digestion mixture for total dissolved phosphorus consisted of sodium hydroxide (1.5 g), potassium peroxidisulfate (5 g) and boric acid (3 g) dissolved in doubly distilled water (100 ml). Seawater samples (50 ml) were mixed with the digestion reagent, heated under pressure at 115-120 °C for 2 h, cooled, and stored before determination in the autoanalyser system. For total phosphorus, extra ascorbic acid was added to the aerosol water of the autoanalyser manifold before the reagents used for the molybdenum blue reaction were added. For measurement of orthophosphate, a phosphate working reagent composed of sulfuric acid, ammonium molyb-... 

The effects of trace concentrations of dissolved organic matter and of orthophosphates (Berner and Morse, 1974) and polyphosphates as "crystal poisons" (e.g., inhibiting the spread of monomolecular steps on the crystal surface by becoming... 

Materials Required Plasma protein solution 2.0 ml mixed phosphate buffer pH 7.0 with azide [To 1000 ml of a solution containing 1.8% w/v of disodium hydrogen orthophosphate and 2.3% w/v of sodium chloride and sufficient of a solution containing 0.78% w/v of sodium dihydrogen orthophosphate and 2.3% w/v of sodium chloride (about 280 ml) to produce a pH of 7.0 Dissolve sufficient sodium azide in the resulting solution to give a 0.02% w/v solution] 1000 ml ... 

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). 

Phosphorus stock standard solution, 1000 pg P O mh (436 pg P mM) -dissolve 1.9173 g potassium dihydrogen orthophosphate, previously dried for 1 h at 105°C, in water. Transfer with beaker washings to a 1-1 volumetric flask, make up to the mark and mix. 

Potassium stock standard solution, 1000 pg K mb - dry potassium dihydrogen orthophosphate (KH2PO4) for 2 h at 105°C, then allow to cool in a desiccator. Weigh 2.889 g into a 100-ml beaker, add sufficient water to dissolve, and transfer to a 1-1 volumetric flask with beaker washings make up to the mark with water and mix. 

Elemental composition Ca 38.76%, P 19.97%, 0 41.26%. Calcium may he analyzed by AA, and ICP, or x-ray methods (see Calcium). The orthophosphate anion may be analyzed by colorimetry (see Phosphorus). For colorimetric analysis the insoluble tribasic phosphate must be brought into aqueous phase hy dissolving in dilute sulfuric acid. 

Europeum generally is produced from two common rare earth minerals monazite, a rare earth-thorium orthophosphate, and bastnasite, a rare earth fluocarbonate. The ores are crushed and subjected to flotation. They are opened by sulfuric acid. Reaction with concentrated sulfuric acid at a temperature between 130 to 170°C converts thorium and the rare earths to their hydrous sulfates. The reaction is exothermic which raises the temperature to 250°C. The product sulfates are treated with cold water which dissolves the thorium and rare earth sulfates. The solution is then treated with sodium sulfate which precipitates rare earth elements by forming rare earth-sodium double salts. The precipitate is heated with sodium hydroxide to obtain rare earth hydrated oxides. Upon heating and drying, cerium hydrated oxide oxidizes to tetravalent ceric(lV) hydroxide. When the hydrated oxides are treated with hydrochloric acid or nitric acid, aU but Ce4+ salt dissolves in the acid. The insoluble Ce4+ salt is removed. 

See how silver nitrate reacts with a solution of sodium orthophosphate. Note the colour of the precipitate. Write the equation of the reaction. Does the substance dissolve in a 1 A nitric acid solution ... 

Thermal Decomposition of Orthophosphates. Roast several crystals of monosubstituted sodium orthophosphate on the lid of a crucible. Continue the decomposition reaction until it terminates (how can this be determined ). Cool the product of roasting, dissolve it in water, and determine the salt of what phosphoric acid is in the solution. Write the equation of the reaction. 

---