Phosphorus buffering

Kuo, R.J. Matijevic, E. (1980) Particle adhesion and removal in model systems. III. Monodisperse ferric oxide on steel. J. Colloid Interface Sci. 78 407-421 Kuo, S. Jellum, E.J. (1994) The effect of soil phosphorus buffering capacity on phosphorus extraction by iron oxide-coated paper strips in some acid soils. Soil Sci. 158 124-131... 

All of these techniques are available, but have not been well researched in terms of their nutrient removal efficiency. One exception is the recent work on the efficiency of buffer zones, which used figures of 10-15% for nitrogen and 20-30% for phosphorus reduction by wooded buffer zones in a study of the Slapton Tey catchment. 

Of the nonmetal oxyanions, those of carbon have a different role in soil than nitrogen and phosphorus. Bicarbonate and carbonate can act as counterions to cations to keep the soil electrically neutral. They are also important because all pH changes in soil tend to involve either carbonate or bicarbonate, and thus, both are involved in soil pH and buffering. 

B. 0. Holmstead1 has carried out investigations on the rate of hydrolysis of cyano-phosphorus compounds. First of all, mention may be made of the hydrolysis of diethyl phosphorocyanidate2 which proceeds rapidly in a buffer solution at pH 7-2 giving rise to the CN ion. Some 90 per cent hydrolysis takes place at this pH in 1 hr. Under similar conditions tabun is also hydrolysed to cyanide to the extent of about 80 per cent in 12 hr. There is a concurrent diminution of toxicity as the hydrolysis proceeds. Even in distilled water 50 per cent of the cyanide is split off in 9 hr. This instability would seem to render this compound ineffective as a toxic agent for use on a large scale. 

Briefly, liposomes (10mM) were incubated for 30minutes at 37°C for egg phosphatidylcholine (EPC) and at 60°C for HSPC-based liposomes with 50 X 10 dpm of methylamine (1 x 10 dpm/mole). At the end of incubation an aliquot of this mixture was passed down a Sephadex G-50 minispin column equilibrated in 10 mM histidine-sucrose buffer 10%, pH 6.7 buffer. Liposomes were eluted at the column void volume and separated from the unencapsulated methylamine. The concentration of liposomes in the original liposomal dispersion and in the void volume fraction was determined from the organic phosphorus (phospholipid) concentration (see section Lipid Quantification and Chemical Stability above) (10,49,53). 

Phosphorus is a critically important element in every cell of the body and also in the form of hydroxyapatite in bone and in all other functions as phosphate. The concentration of phosphate in blood is 1.0 to 1.5 mmol/L existing as H2P0( and HPOl" the equilibrium between the two acts as a proton buffer... 

For determination of total P-phosphorus incorporation, filter the precipitate over a glass fiber filter and count for radioactivity. If electrophoresis is intended, collect the precipitate by centrifugation with 5000 X g and dissolve the pellet in the appropriate sample buffer. Choose the electrophoresis system with respect to the different pH stability of phosphorylation products. 

Takakura, K. Maezawa, H. Kobayashi, K. Hieda, K. Strand breaks in DNA in buffered solution induced by monochromatic X-rays around the K-shell absorption edge of phosphorus. In Synchrotron Radiation in Biosciences. Chance, B., Deisenhofer, J., Ebashi, S., Goodhead, D.T., Helliwell, J.R., Huxley, H.E., lizuka, T., Kirz, J., Mitsui, T., Rubenstein, E., Sakabe, N., Schmahl, G., Stuhrmann, H.B., Wuthrich, K., Zaccai, G., Eds. Oxford University Press Oxford, 1994 756-764 pp. 

The extremely low solubility of lead phosphate in water (about 6 x 10 15m) again suggests potentiometric analysis. Selig57,59 determined micro amounts of phosphate by precipitation with lead perchlorate in aqueous medium. The sample was buffered at pH 8.25-8.75 and a lead-selective electrode was used to establish the end-point. The detection limit is about 10 pg of phosphorus. Anions which form insoluble lead salts, such as molybdate, tungstate or chromate, interfere with the procedure. Similar direct potentiometric titrations of phosphate by precipitation as insoluble salts of lanthanum(III), copper(II) or cadmium(II) are suggested, the corresponding ion-selective electrodes being used to detect the end-point. 

Differences in pH and buffering capacity among individual lots of fresh milk reflect compositional variations arising from the functions of the mammary gland. In general the pH is lower in colostrum (down to pH 6.0 McIntyre et al. 1952) and higher in cases of mastitis (up to pH 7.5 Prouty 1940) than in normal milk of mid-lactation. As discussed in Chapter 1, colostrum and mastitis milks are known to differ radically in their proportions of the proteins and certain salts. Milks of lower phosphorus, casein, and Ca2+ tend to be low in titratable acidity, while excessive acidity is related to hyperketonemia, inadequate calcium and excessive concentrates in the ration (Bonomi 1978). 

The hydrolysis reactions of A -phospho amino acids seen as models for protein dephosphorylation have been studied in Tris-HCl buffer (pH7.5)-DMSO. The reactions were first order and the rates were very much faster than those of simple phosphoamidates. A pentacoordinated phosphorus intermediate is proposed on the reaction pathway.265 The rates of ester exchange reactions of alcohols (nucleoside models) with the oxyphosphorane (299) have been studied and the rates of exchange are much faster for diols than for mono-alcohols.266... 

Calcium and phosphorus influence curd buffering properties and ripening characteristics. The calcium content in cheese may be determined by... 

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