Phosphates, additives ortho

The solvent action of mineral oil base stocks can cause skin problems and prolonged exposure may have been the origin of a few skin cancers . The use of additives that might be in any way harmful to health, e.g. ortho-tricresyl phosphate (anti-wear) and sodium mercaptobenzothiazole (anticorrosion) has been discontinued where skin contact is likely. 

The calcium phosphate solubility constant [KCa3(P04)2] is extremely small and phosphate quickly reacts with calcium when present in warm to hot, alkaline BW in the ortho- form. This reaction is complete and superior to the soda ash precipitation reaction. In addition, calcium phosphate is stable and does not decompose. 

Organophosphate Ester Hydraulic Fluids. The physical and chemical property information available for the organophosphate ester hydraulic fluid products and components is presented in Tables 3 A, 3-5, 3-8, and 3-9. Much of this information was abstracted from trade literature or data taken from material safety data sheets. While there is information on many of the major component chemicals in the hydraulic fluid products, there can still be major data uncertainties for products that involve mixtures of different components. While current manufacturing practices aim to minimize or eliminate the presence of such worrisome components as th-ortho-cresyl phosphate, there remain major uncertainties about the composition and properties of older products, which would be more commonly encountered as site contaminants at NPL sites. Additional information on physical and chemical properties for organophosphate ester hydraulic fluid products is, therefore, an important data need. 

Condensed (poly) phosphates may exert different effects on calcium utilization than the aforementioned effects of simple (ortho-) phosphates. Polyphosphates have a much greater affinity for calcium than do orthophosphates, and soluble calcium-polyphosphate complexes are readily formed in the gastric and intestinal environments. In addition, polyphosphates must be hydrolyzed by an intestinal alkaline phosphatase (27) prior to absorption. We have found polyphosphates to be incompletely (80.5%) hydrolyzed to orthophosphate during the digestive process in young adult males when calcium intake was low only 56% of a 1 g phosphorus supplement was absorbed from a polyphosphate sources as compared to 71% from an orthophosphate source (5). 

Phosphorus(V) oxide is very hygroscopic and the bottle must be closed except when an addition is made. The reactor is cooled with ice water so that the reaction temperature is maintained at 5-10°. Methanol (125 mL)is added drop-wise to the stirred solution to precipitate the crude ammonium tetrametaphos-phate, which is collected by suction filtration, washed with methanol, and dried in vacuum over anhydrous CaS04. The product weighs 33 g and contains about 65% of its phosphorus as tetrametaphosphate. The remainder is a mixture of ortho-, trimeta- and short-chain phosphates. Any lumps are crushed and the crude ammonium tetrametaphosphate is spread in a no. 1 porcelain evaporating dish and heated for 2 hours at 240° in a slow stream,of anhydrous ammonia (about 100 mL/min or 3-5 g/hr). Care is taken to avoid absorption of moisture before or during heating, as this adversely affects the formation of the product. 

These reactions are reversible, and removal of the caustic alkali by addition of acids effects the immediate conversion of ortho- or pyro-salts into the meta-salts. On the other hand, the presence of a large excess of caustic alkali favours the formation of the ortho- and pyro-salts. The order of stability is the reverse of that which applies to the ortho-, pyro-, and meta-phosphates. Orthophosphates are prepared from the other two classes either by boiling or by addition of weak acids. 

In 1950 Seligman and his co-workers (S13) suggested the use of sodium j8-naphthyl phosphate as a substrate for the determination of acid or alkaline phosphatase activity. For the former, 1 ml of 1 20 diluted serum was added to 5 ml of 0.4 mM sodium 8-naphthyl phosphate in 0.1 M acetate buffer of pH 4.8, and the reaction was allowed to proceed for 2 hours at 37.5°C. The addition of 4 drops of IM sodium carbonate solution served to retard the reaction as well as to raise the pH to the optimal level for coupling with 1 ml of a solution of tetrazotized ortho-dianisidine. After 3 minutes, the protein was precipitated with trichloroacetic acid, the dye extracted with ethyl acetate, and the color density determined in the region of 540 nm. The unit of phosphatase activity was defined as that amount of enzyme which liberates the color equivalent of 10 ml of j8-naphthol per hour at 37.5° in 1 hour. The serum acid phosphatase in a group of normal adults ranged from 0.7 to 1.6 units and averaged 1.0 unit per 100 ml of serum. 

The alteration of mineral and casein equilibria is reflected in changes to the physical properties of milk. The addition of citrate and different types of phosphates (ortho-, pyro-, or hexameta) to milk protein concentrate solutions, which alters the distribution of calcium and inorganic phosphate between the colloidal and serum phases of milk, affects its turbidity and buffering capacity (Mizuno and Lucey, 2005). The turbidity is affected because dissolution of colloidal calcium phosphate is accompanied by release of caseins into the serum. 

Another excellent antiwear compound is tricresyl phosphate (TCP). These compounds are used as a high-temperature antiwear and extreme pressure additive. Tricresyl phosphate is an organophosphate made from cresol and phosphorus oxychloride (shown in Figure 7.5). These compounds come in the ortho-, meta-, and para-cresyl phosphates. They are also used as gasoline additives [4],... 

Treatment of adenosine 5 -[ 3-morpholino]diphosphate with P 04]ortho-phosphate affords [y- 04]ATP, which has been used to study non-enzymatic hydrolytic pathways of ATP. Upon hydrolysis, the orthophosphate released was isolated, converted to trimethyl phosphate, and the isotope content analysed by mass spectrometry. In 1m and 0.1m HCl, the data suggest addition-elimination as the hydrolysis mechanism, with attack occurring predominantly at Py to... 

Corrective water treatments of Glasgow s water supplies were applied in 1979 (lime to raise pH) and again in the mid-1980s (additional dosing of ortho-phosphate). Table 4.2 summarises the reductions in water lead and blood lead that were achieved, based on the study by Moore et al. (1998). In another study by Watt et al. (2000), the geometric mean blood lead concentration in the year 2000 had fallen to 3.7 pg/dl compared to 11.9 pg/dl 12 years previously. 

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