Oxygen quantitative extraction

In one method, the metal ion is incorporated into a bulky molecule and then associates with another ion of the opposite charge to form an ion pair, or the metal ion associates with another ion of great size (organiclike). For example, it is well known that iron(III) can be quantitatively extracted from hydrochloric acid medium into diethyl ether. The mechanism is not completely understood, but evidence exists that the chloro complex of the iron is coordinated with the oxygen atom of the solvent (the solvent displaces the coordinated water), and this ion associates with a solvent molecule that is coordinated with a proton ... 

Poloxamers are used primarily in aqueous solution and may be quantified in the aqueous phase by the use of compleximetric methods. However, a major limitation is that these techniques are essentially only capable of quantifying alkylene oxide groups and are by no means selective for poloxamers. The basis of these methods is the formation of a complex between a metal ion and the oxygen atoms that form the ether linkages. Reaction of this complex with an anion leads to the formation of a salt that, after precipitation or extraction, may be used for quantitation. A method reported to be rapid, simple, and consistently reproducible [18] involves a two-phase titration, which eliminates interferences from anionic surfactants. The poloxamer is complexed with potassium ions in an alkaline aqueous solution and extracted into dichloromethane as an ion pair with the titrant, tet-rakis (4-fluorophenyl) borate. The end point is defined by a color change resulting from the complexation of the indicator, Victoria Blue B, with excess titrant. The Wickbold [19] method, widely used to determine nonionic surfactants, has been applied to poloxamer type surfactants 120]. Essentially the method involves the formation in the presence of barium ions of a complex be-... 

A PET oligomer isolation method has utilised chloroform extraction in a Parr bomb lined with a Teflon-TFE fluoro-carbon resin [40]. The analytics of fluoropolymer processing aids (combustion analysis, XRF, EUR, 19F NMR, OM) have recently been described [29]. Combustion analysis (Parr Oxygen Bomb Calorimeter) can be used for quantitative analysis... 

Quantitative kinetic data showed that photosensitized oxygenations of various pollutants (e.g., 2,5-dimethylfuran and the insecticide Disulfoton) in air-saturated natural water samples containing aquatic HS and in distilled water containing soil-extracted or commercial HA/FA were at least one order of magnitude faster than those in distilled water. 

Other Iron Compounds of Biological Interest.—The valency of iron in a range of ferredoxin extracts has been determined by ESCA. The structure of the Fe—S complex in a bacterial ferredoxin has been determined. The iron and sulphur atoms occupy alternate corners of a cube and four more sulphur atoms project from the iron atoms.Admission of oxygen to a neutral solution of Fe and excess penicillamine gives a red bis-complex, which is relatively stable in aqueous solution at room temperature. Quantitative... 

In their test system, the researchers used the ionic liquid l-butyl-3-methylimidazol-ium hexafluorophosphate (bmim)(PF6), which is stable in the presence of oxygen and water, with naphthalene as a low-volatility model solute. Spectroscopic analysis revealed quantitative recovery of the solute in the supercritical CO2 extract with no contamination from the ionic liquid. They found that CO2 is highly soluble in (bmim)(PF6) reaching a mole fraction of 0.6 at 8 MPa, yet the two phases are not completely miscible. The phase behavior of the ionic liquid-C02 system resembles that of a cross-linked polymer-solvent system (Moerkerke et al., 1998), even though... 

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