Phosphate estimation

The determination of phosphate clearance is a very simple procedure whieh involves only phosphate estimations. However, it is almost certainly too crude to be useful. In a recent series (R5), it yielded very poor discrimination between hyperparathyroid and euparathyroid subjects (Fig. 11). It would probably be improved by the introduction of a correction for plasma level, but, even so, precision requires catheterization which is undesirable in a routine test. 

Experimental protocols for absorbance measurements of a few substances insist that the measurement be done within a very short time of color development. One good example is the Fiske Subbarow method of phosphate estimation by the ANSA method. The reason for this Insistence is simple — some colored compounds are imstable and imdergo changes within quite short times. In such cases the color could increase, or decrease. Even more detrimental is the fact that for some such imstable compoimds, even the may change. 

Blood samples for inorganic phosphate estimation should be rapidly separated as phosphate diffuses from the cells following the enzymic hydrolysis of phosphate esters. It is therefore advantageous to collect such blood specimens in containers having a fluoride preservative. This inhibits the enzymatic hydrolysis. Several methods are available for inorganic phosphate estimation. 

Other methods of phosphate estimation are based on its reaction with molybdate and vanadate to give yellow phos-phomolybdovanadate which can be estimated colorimetrically. 

Arsenic occurs in sea water to the extent of about 11 to 20 mg. As per cubic metre, and has frequently been included in phosphate estimations by mistake (Atkins, 1927). 

Flpet an aliquot Into an extraction vessel, and adjust the add and nitrate contents as In Treatment C. Add sufficient alumlnvun nitrate to complex the fluoride and phosphate estimated to be present. The total volume should be 12 ml. or less. 

A first approach to testing, ASTM D 1094, is to create, using a potassium phosphate reagent, a separation between two layers, hydrocarbon and aqueous. The degree of separation of the two phases is estimated by attributing a grade from 1 to 3 and the appearance of the interface by five levels of observation 1, lb, 2, 3, and 4. The specifications establish both the quality of separation (2 is the maximum) and the appearance of the interface (lb maximum). 

A detailed and weU-defined estimate of world phosphate resources and reserves was prepared in 1979 (105). A summary is presented in Table 14. 

Bilhons of metric tons of phosphate rock also are present offshore in the oceans, eg, best estimates are that a biUion tons of pellets that may contain about 30% P2 5 present in a Baja California—Mexico deposit alone. Other areas in the world that contain large, unevaluated amounts of phosphate include AustraUa, Alaska, Africa, the Near East, Pern, Colombia, Brazil, the People s RepubHc of China, MongoHa, and the former Soviet Union. 

Although synthetic lubrication oil production amounts to only about 2% of the total market, volume has been increasing rapidly (67). Growth rates of the order of 20% per year for poly( a-olefin)s, 10% for polybutenes, and 8% for esters (28) reflect increasing automotive use and these increases would accelerate if synthetics were adopted for factory fill of engines by automotive manufacturers. The estimated production of poly( a-olefin)s for lubricants appears to be approximately 100,000 m /yr, esters 75,000, poly(alkylene glycol)s 42,000, polybutenes 38,000, phosphates 20,000, and dialkyl benzene 18,000 (28,67). The higher costs reflected in Table 18 (18,28) have restricted the volume of siUcones, chlorotrifluoroethylene, perfluoroalkylpolyethers, and polyphenyl ethers. 

Estimates of speculative lesouices (SR) at 130/kg uianium and those having an unassigned cost range are provided ia Table 4 (23). These resources, which total about 11.28 x 10 t, would be ia addition to the reasonably assured and estimated additional resources. Estimates of uranium resources from unconventional and by-product sources are presented ia Table 5 (24). These resources total about 7 x 10 t for phosphates, 0.013 x 10 t for nonferrous ores, 0.016 x 10 t for carbonates, and 0.014 x 10 t for lignites. These would be ia addition to the reasonably assured resources, estimated additional resources, and the speculative resources (24). 

Estimated world production capacity for elemental phosphoms is shown in Table 5 (6). Three elemental phosphoms production sites remain operational in North America (14), although Rhc ne Poulenc has announced its intention to cease production in late 1995. The remaining plants have survived owing to the availabiUty of economical electric power in the Northwest and proximity to phosphate ore deposits, resulting in lower cost phosphoms. The capacity of these producers in 1995 was estimated to be 264,000 metric tons. U.S. production capacity peaked at approximately 622,000 metric tons in 1970. 

The decrease ia wodd sulfur iaveatories eaded ia the period 1990—1992. From 1991 to 1992, sulfur iaveatories remaiaed relatively stable. However, wodd sulfur iaveatories ia 1993 iacreased sharply, to an estimated 11.8 million metric tons. This iacrease was caused by a sharp fall ia wodd demand for phosphate fertilizers, which, because of market conditions, led to a large iacrease ia vattiag sulfur, especially ia Canada. Figure 3 shows wodd sulfur iaventory levels ia the maia produciag couatries or regioas from 1980 through 1994. 

Economic Aspects. Sodium hypochlorite—trisodium phosphate complex was commercialized in 1930. Chlorinated TSP is manufactured by Stauffer (a subsidiary of Rhc ne-Poulenc, Inc.). The consumption, steadily decreasing since 1980, dropped sharply in 1985 because of reduced use in dishwasher detergents. The estimated demand in 1987 was 37,360 t (220). In 1988 it sold for 0.32/lb ( 0.70/kg) for tmddoad quantities of 660 kg (300-lb) dmms. 

In one patent (31), a filtered, heated mixture of air, methane, and ammonia ia a volume ratio of 5 1 1 was passed over a 90% platinum—10% rhodium gauze catalyst at 200 kPa (2 atm). The unreacted ammonia was absorbed from the off-gas ia a phosphate solution that was subsequently stripped and refined to 90% ammonia—10% water and recycled to the converter. The yield of hydrogen cyanide from ammonia was about 80%. On the basis of these data, the converter off-gas mol % composition can be estimated nitrogen, 49.9% water, 21.7% hydrogen, 13.5% hydrogen cyanide, 8.1% carbon monoxide, 3.7% carbon dioxide, 0.2% methane, 0.6% and ammonia, 2.3%. 

When saccharin is treated with diethyl phosphorothiolothionate, the 3-ethylmercapto compound is obtained, rather than the expected organophosphorus compound (77 ACS(B)460). Treatment of saccharin with phosphorus pentoxide and amines gives 3-(substituted-amino)-1,2-benzisothiazole 1,1-dioxides, via an intermediate phosphate (81ZN(B)1640). Reduction of saccharin with zinc and hydrochloric acid gives 2,3-dihydro-l,2-benzisothiazole 1,1-dioxide, the method being used to estimate saccharin in foodstuffs (75MI41701). 

Table 12.1 Estimated reserves of phosphate rock (in gigatonnes of contained P)...

In addition to its presence as the free element in the atmosphere and dissolved in surface waters, oxygen occurs in combined form both as water, and a constituent of most rocks, minerals, and soils. The estimated abundance of oxygen in the crustal rocks of the earth is 455 000 ppm (i.e. 45.5% by weight) see silicates, p. 347 aluminosilicates, p. 347 carbonates, p. 109 phosphates, p. 475, etc. 

In 1826 J. J. Berzelius found that acidification of solutions containing both molybdate and phosphate produced a yellow crystalline precipitate. This was the first example of a heteropolyanion and it actually contains the phos-phomolybdate ion, [PMoi204o] , which can be used in the quantitative estimation of phosphate. Since its discovery a host of other heteropolyanions have been prepared, mostly with molybdenum and tungsten but with more than 50 different heteroatoms, which include many non-metals and most transition metals — often in more than one oxidation state. Unless the heteroatom contributes to the colour, the heteropoly-molybdates and -tungstates are generally of varying shades of yellow. The free acids and the salts of small cations are extremely soluble in water but the salts of large cations such as Cs, Ba" and Pb" are usually insoluble. The solid salts are noticeably more stable thermally than are the salts of isopolyanions. Heteropoly compounds have been applied extensively as catalysts in the petrochemicals industry, as precipitants for numerous dyes with which they form lakes and, in the case of the Mo compounds, as flame retardants. 

Suppose we need to estimate the pH of an aqueous solution of a fully deproto-nated polyprotic acid molecule. An example is a solution of sodium sulfide, in which sulfide ions, S2-, are present another example is a solution of potassium phosphate, which contains P04 ions. In such a solution, the anion acts as a base it accepts protons from water. For such a solution, we can use the techniques for calculating the pH of a basic anion illustrated in Example 10.11. The K, to use in the calculation is for the deprotonation that produces the ion being studied. For S2, we would use Ki2 for H2S and, for P043-, we would use Kai for H3P04. 

In contrast, another group35 found that extracts of E. coli contained a mixture of pentulose phosphates at a concentration near 0.3 nmol per mg of the dry weight of cells. The sugars were estimated by gas chromatography-mass spectrometry after treatment of the extract with phosphatase followed by silylation, or borohydride reduction and acetylation. Furthermore, a partially purified preparation from these extracts catalyzed the synthesis of 1-deoxypentulose... 

Equation (52) allows us to estimate the impact of viscoelastic braking on the capillary flow rate. As an example, we will consider that the liquid is tricresyl phosphate (TCP, 7 = 50 mN-m t = 0.07 Pa-s). The viscoelastic material is assumed to have elastic and viscoelastic properties similar to RTV 615 (General Electric, silicone rubber), i.e., a shear modulus of 0.7 MPa (E = 2.1 MPa), a cutoff length of 20 nm, and a characteristic speed, Uo, of 0.8 mm-s [30]. TCP has a contact angle at equilibrium of 47° on this rubber. 

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