Phosphoms fractionation

Daroub SH, Ellis BG, Robertson GP (2001) Effect of cropping and low-chemical input systems on soil phosphoms fractions. Soil Sci 166 281-291 Dick RP, Breakwell DP, Turco RF (1996) Soil Enzyme Activities and Biodiversity Measurements as Integrative Microbiological Indicators. SSSA Special Pub 49 247-272... 

The amount and physical character of the char from rigid urethane foams is found to be affected by the retardant (20—23) (see Foams Urethane polymers). The presence of a phosphoms-containing flame retardant causes a rigid urethane foam to form a more coherent char, possibly serving as a physical barrier to the combustion process. There is evidence that a substantial fraction of the phosphoms may be retained in the char. Chars from phenohc resins (qv) were shown to be much better barriers to pyrolysate vapors and air when ammonium phosphate was present in the original resin (24). This barrier action may at least partly explain the inhibition of glowing combustion of char by phosphoms compounds. 

The heavy mineral sand concentrates are scmbbed to remove any surface coatings, dried, and separated into magnetic and nonmagnetic fractions (see Separation, magnetic). Each of these fractions is further spHt into conducting and nonconducting fractions in an electrostatic separator to yield individual concentrates of ilmenite, leucoxene, monazite, mtile, xenotime, and zircon. Commercially pure zircon sand typically contains 64% zirconium oxide, 34% siUcon oxide, 1.2% hafnium oxide, and 0.8% other oxides including aluminum, iron, titanium, yttrium, lanthanides, uranium, thorium, phosphoms, scandium, and calcium. 

The total phosphoms content of the sample is determined by method AOCS Ja 5-55. Analysis of phosphoUpid in lecithin concentrates (AOCS Ja 7-86) is performed by fractionation with two-dimensional thin-layer chromatography (tic) followed by acid digestion and reaction with molybdate to measure total phosphorous for each fraction at 310 nm. It is a semiquantitative method for PC, PE, PI, PA, LPC, and LPE. Method AOCS Ja 7b-91 is for the direct deterrnination of single phosphoHpids PE, PA, PI, PC in lecithin by high performance Hquid chromatography (hplc). The method is appHcable to oil-containing lecithins, deoiled lecithins, lecithin fractions, but not appHcable to lyso-PC and lyso-PE. 

Catalysts commonly lose activity in operation as a result of accumulation of materials from the reactant stream. Catalyst poisoning is a chemical phenomenon, A catalyst poison is a component such as a feed impurity that as a result of chemisorption, even in smaH amounts, causes the catalyst to lose a substantial fraction of its activity. For example, sulfur compounds in trace amounts poison metal catalysts. Arsenic and phosphoms compounds are also poisons for a number of catalysts. Sometimes the catalyst surface has such a strong affinity for a poison that it scavenges it with a high efficiency. The... 

REE phosphates and 6.56 flux and maximum foraminiferal CaC03-P content from Palmer, 1985) Comments Any phosphoms associated with CaC03 tests, not surface metal oxyhydroxide coatings, is included in the quantity measured by step III of the SEDEX method this estimate serves as a measure of the fraction of the step III, or the burial flux of authigenic apatite + hiogenic apatite + CaCOs, that can be accounted for by burial of CaC03. Rasmussen, 2000 (determined for ancient marine... 

Sedimentary organic phosphorus composition and reactivity. Organic phosphoms (Porg) is the primary vector of phosphoms delivery to marine sediments, and constitutes an important fraction (—25-30%) of total phosphoms buried in marine sediments (Froelichetfll., 1982 Ruttenberg, 1993 Colman and Holland, 2000). Despite its importance to the total marine sedimentary phosphoms... 

Volatile Phosphorus, a Small Part of Available Phosphorus—As noted previously, the PEI data of RO 780 showed no fiirther generation of phosphorus with more lengthy exposures (and, in fact indicated some decrease in PEI at 50 and 60 min exposure). Thus, whatever volatile decomposition products were produced before 10 min exposure comprised only a small fraction of the phosphoms-containing additive(s) present in the fresh oil. That is, 850 g of the fresh RO 780 contains 966 PPM phosphorus or approximately 820 mg/L, whereas the PEI is 9 mg/L -about 1 % of the phosphoms in the fresh RO 780 volatilized in this test. 

Samec and coworkers have differentiated between the fractions on the basis of phosphoms content. Undoubtedly, organic phosphate is associated primarily with the B-fraction of potato starch, contributing polarity to that component. In the case of com starch, the distinction is not as sharp, since the total phosphoms content is very much lower. Also, it is possible to separate the B-fraction of com starch into subtractions of high and low phosphoms content, and these do not differ materially in. solubility behavior or alkali lability. Thus phosphoms is believed to constitute only a minor difference between the fractions. 

In marked contrast to tri-covalent nitrogen, tri-covalent phosphoms has a significant barrier to pyramidal inversion, as discussed in section 10.2. In C-substituted phospholanes and the 4-membered phosphetanes as well, cis,trans isomers are stable and separated easily. This possibility was not recognized until it was demonstrated in 1965 that 1,2-dimethyl derivatives 10.12 and 10.13 of dihydrophospholes, which are known as 3-phospholenes, could be separated by fractional distillation or gas chromatography. ... 

Peppard, D.F., 1964, Fractionation of rare earths by liquid-liquid extracion using phosphoms-based extractants, in Progress in the Science and Technology of the Rare Earths, Vol. 1, ed. L. Eyring (Pergamon Press, New York, 1964) pp. 89-109. 

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