Phosphorus partitioning

Clark, J.H., K.C. Olson, T.B. Schmidt, M.L. Linville, D.O. Alkire, D.L. Meyer, G.K. Rentfrow, C.C. Carr, and E.P. Berg, 2007. Effects of dry matter intake restriction on diet digestion, energy partitioning, phosphorus retention, and ruminal fermentation by beef steers. J. Anim. Sei. 85, 3383-3390. 

For multi-analyte and/or multi-matrix methods, it is not possible to validate a method for all combinations of analyte, concentration and type of sample matrix that may be encountered in subsequent use of the method. On the other hand, the standards EN1528 andEN 12393 consist of a range of old multi-residue methods. The working principles of these methods are accepted not only in Europe, but all over the world. Most often these methods are based on extractions with acetone, acetonitrile, ethyl acetate or n-hexane. Subsequent cleanup steps are based on solvent partition steps and size exclusion or adsorption chromatography on Florisil, silica gel or alumina. Each solvent and each cleanup step has been successfully applied to hundreds of pesticides and tested in countless method validation studies. The selectivity and sensitivity of GC combined with electron capture, nitrogen-phosphorus, flame photometric or mass spectrometric detectors for a large number of pesticides are acceptable. 

For cottonseeds, pyrithiobac-sodium is extracted with acetone-water (4 1, v/v). After filtration, the acetone is removed by evaporation under reduced pressure. The residue is adjusted to pH 1 and extracted with ethyl acetate. The extract is cleaned up by liquid-liquid partitioning and methylated with diazomethane. The methyl ester of pyrithiobac is purified by silica gel column chromatography. Pyrithiobac-methyl is determined by gas chromatography (GC) with nitrogen-phosphorus detection (NPD). 

Water samples are directly partitioned with dichloromethane (DCM). The DCM exAact is then rotary evaporated and driven to dryness with a sAeam of niAogen. The dry residue is dissolved in acetone and analyzed by gas chromatography/nitrogen-phosphorus detection (GC-NPD). 

Residues are extracted with acetone. The extract is rotary evaporated to remove acetone, the concentrated residue is diluted with 5% aqueous sodium chloride, and residues are partitioned into dichloromethane. The extract is then concentrated and purified on a silica gel column. Residues of pyriproxyfen are quantitated by gas chromatography with nitrogen-phosphorus detection (GC/NPD). For citrus, a hexane-acetonitrile solvent partition step is required for oil removal prior to the dichloromethane partition step. 

Partitioning of carbocations between addition of nucleophiles and deprotonation, 35, 67 Perchloro-organic chemistry structure, spectroscopy and reaction pathways, 25, 267 Permutational isomerization of pentavalent phosphorus compounds, 9, 25 Phase-transfer catalysis by quaternary ammonium salts, 15, 267 Phosphate esters, mechanism and catalysis of nucleophilic substitution in, 25, 99 Phosphorus compounds, pentavalent, turnstile rearrangement and pseudoration in permutational isomerization, 9, 25... 

Overall, the large number of significant differences among the fractions of all three bean types, reveals that the various minerals studied were not equally distributed among the fractions, except for sodium, but rather that partitioning occurred. Consistent with the ash values obtained, the protein flour fractions of the three bean types contained larger amounts of Fe, Mg, P, Z, and K whereas the starch II fractions contained smaller amounts of these minerals and Ca and Cu than the other flour fractions. Phytic acid content ranged from 8.7-30.2 mg/g for navy flours, from 4.3-23.7 mg/g for pinto flours. Total phosphorus content correlated well with both phytic acid content and protein content. Phytic acid content was... 

When compound (VII) was heated to 130° for 2-5 hr. it isomerized to OO -diethyl S-ethylmercaptoethyl phosphoro-thiolate (VIII). This was shown by successive partitioning of the heated product between suitable solvents, the partition ratios of the radioactive phosphorus being determined after each extraction. If only one compound is present all the ratios would be the same if two or more compounds are present, the observed over-all partition ratios would change in systematic fashion. 

The dipole moment of phosphabenzene is reinforced by the methyl group shown in (147) and increases it from 1.46 to 1.77 D thus it resembles pyridine, which has the heteroatom at the negative end of the dipole.181 The magnitudes and trends of the dipole moments of the methylphosphines have been investigated by MO studies and the dipoles partitioned into bond moments, bond polarization, and lone-pair moments.182 The reciprocal effects of the double bond and the phosphorus atom in... 

The model-calculated partitioning of the human-induced perturbation fluxes In the global coastal margin of (a) nitrogen and (b) phosphorus for the period from 1850 to the present (2000) and projected to 2035 under the business-as-usual scenario, In units of lO mol/y and Mtons/y. The anthropogenic sources are plotted on the (-) side and the resulting accumulations and enhanced export fluxes are plotted on the +) side. Source-. From Mackenzie, F. T, et al. (2002). Chemical Geology 190, 13-32. 

ChemicaPPhysical. Emits toxic fumes of phosphorus, nitrogen, and sulfur oxides when heated to decomposition (Sax and Lewis, 1987). Methidathion oxon was also found in fogwater collected near Earlier, CA (Glotfelty et ah, 1990). It was suggested that methidathion was oxidized in the atmosphere during daylight hours prior to its partitioning from the vapor phase into the fog. On 12 January 1986, the distributions of parathion (0.45 ng/my in the vapor phase, dissolved phase, air particles, and water particles were 57.5, 25.4, 16.8, and 0.3%, respectively. For methidathion oxon (0.84 ng/m3), the distribution in the vapor phase, dissolved phase, air particles, and water particles were <7.1, 20.8, 78.6, and 0.1%, respectively. 

In general, soluble and nom-eactive contaminants are found mainly in dissolved form in runoff water. For example, a large percentage (up to 90%) of the most soluble herbicides present in the soil layer may be partitioned in overland flowing water. A substantial portion of dissolved nitrogen (8-80%) and phosphorus (7-30%) also may be transported in runoff water (Menzel et al. 1978 Hubbard et al. 1982 ... 

The study of the monoanions of a third class of phosphorus-containing monoesters, the phosphoramidates, has been restricted for the present to p- and o-substituted aryl phosphoramidates, and phosphoramidate and its O-methyl derivatives13-16. Two striking differences from the behavior of O- and S-phos-phate monoester monoanions are noted in the experimental criteria compiled in order to postulate mechanism (a) solvolysis in mixed organic solvents, particularly 50% v/v dioxan-water, results in a 50% decrease in the rate of hydrolysis of o- and p-substituted aryl phosphoramidate monoanions and all ionic forms of phosphoramidate and its O-methyl derivatives excepting the parent monoanion, and (b) partitioning of the aryl phosphoramidates and phos-... 

Equations 17—20 result from contact between hot metal and slag, and the sulfur and carbon come dissolved in the hot metal. Likewise, the manganese, silicon, and phosphorus which are produced are dissolved into the hot metal. The heats of solution for these elements in some cases depend on concentration, and are not included in the heats of reaction listed above. The ratio of the concentration of the oxide (or element for sulfur) in the slag to the concentration of the element in the hot metal is the partition ratio, and is primarily a function of slag chemistry and temperature. 

Pyrethroids, organo-phosphorus types Vegetables Ethanol extraction, partitioning with toluene, Florisil clean-up GC - [105]... 

To test the generality of the jr-distortivity phenomenon and of the Valence Bond model for delocalization, it is of interest to apply the o-it partition to conjugated molecules other -than hydrocarbons, e.g. containing nitrogen, silicon or phosphorus atoms that we have kept in a constrained planar geometry. The total distortion energies, as well as their a and it components are displayed in Table 3, as calculated at the 6-31G/it-CI level. 

Environmental Fate. Elemental phosphorus partitions from water to sediment (Berkowitz et al. 1981) transporting elemental phosphorus to sediment. Volatilization from water and soil transports small amounts of elemental phosphorus to air (Spanggord et al. 1985 ... 

C) Preparation of 7-Chloro-2,3-Dihydro-l-Methyl-5-Phenyl-lH-l,4-Benzodiazepine A mixture of 4.7 g (22.6 mol) of 7-chloro-l,2,3,4-tetrahydro-l-methyl-5H-l,4-benzodiazepin-5-one and 100 ml of phosphorus oxychloride was heated in an oil bath at 100°C for 15 minutes. The solution was concentrated to dryness in vacuo. The residue was partitioned between methylene chloride and cold saturated sodium bicarbonate solution. The methylene chloride phase was dried over sodium sulfate and sodium bicarbonate, filtered, diluted with benzene and concentrated in vacuo to produce crude 5,7-dichloro-2,3-dihydro-l-methyl-lH- 1,4-benzodiazepine. 

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