Chelating agents selection

Selected Chelating Agents for the Fluorometric Analysis of Inorganic Metal Ions... 

An ion-selective electrode in which a chelating agent is incorporated into a hydrophobic membrane. 

Capillary Electrophoresis. Capillary electrophoresis (ce) is an analytical technique that can achieve rapid high resolution separation of water-soluble components present in small sample volumes. The separations are generally based on the principle of electrically driven ions in solution. Selectivity can be varied by the alteration of pH, ionic strength, electrolyte composition, or by incorporation of additives. Typical examples of additives include organic solvents, surfactants (qv), and complexation agents (see Chelating agents). 

The nature of the donor atoms in the chelating agent. Ligands which contain donor atoms of the soft-base type form their most stable complexes with the relatively small group of Class B metal ions (i.e. soft acids) and are thus more selective reagents. This is illustrated by the reagent diphenylthiocarbazone (dithizone) used for the solvent extraction of metal ions such as Pd2+, Ag+, Hg2+, Cu2+, Bi3+, Pb2+, and Zn2 +. ... 

The procedure followed entails the removal of gross interferences by solvent extraction, and the selective extraction and concentration of the trace metal by use of a chelating agent. The alloy used should not contain more than 0.1 g of copper in the sample weighed out. 

The monolithium salt of 4-hydroxy-4-(phenylethynyl)-2.5-cyclohexadienone (12), prepared in situ by the addition of lithium acetylide to /7-benzoquinone, was treated with methylmagnesium chloride in l HF-TMEDA or in THF —DMPU. The syn-, 4-addition adduct 13, derived from intramolecular delivery of the carbon nucleophile by the hydroxy oxygen, as well as the <7s-1,4-diol 14, obtained via intermolecular 1,2-addition, were obtained in varying amounts depending on the conditions. The selectivity on 1,4- to 1,2-addition increased by the addition of cation chelating agents such as DMPU, TMEDA, and 15-crown-5. Although the 1,4 to 1,2... 

These compounds should be dissolvable in a clean-up solution containing a quaternary organic ammonium salt, or simply ammonium chloride [1749]. The solubilities of some selected particulate bridging agents are shown in Table 9-1. A chelating agent such as citric acid or its salts is also included in the clean-up solution. 

The carbonate-bound trace elements are usually extracted by NaOAc-HOAc (Tessier et al., 1979 Hickey and Kittrick, 1984 Banin et. al., 1990 and Han et al., 1992) or by using chelating agents, such as EDTA (Sposito et al., 1982 Emmerich et al., 1982 Miller and Mcfee, 1983 Chang et al., 1984 Knudtsen and O Connor, 1987 McGrath and Cegarra, 1992). Generally, EDTA lacks the required specificity and selectivity for carbonate phase extractions and tends to extract metals from a number of soil components. 

Effects of Chelating Agents on the Selectivity and Space-Time Yield of Hydrocarbon3... 

The book focuses on three main themes catalyst preparation and activation, reaction mechanism, and process-related topics. A panel of expert contributors discusses synthesis of catalysts, carbon nanomaterials, nitric oxide calcinations, the influence of carbon, catalytic performance issues, chelating agents, and Cu and alkali promoters. They also explore Co/silica catalysts, thermodynamic control, the Two Alpha model, co-feeding experiments, internal diffusion limitations. Fe-LTFT selectivity, and the effect of co-fed water. Lastly, the book examines cross-flow filtration, kinetic studies, reduction of CO emissions, syncrude, and low-temperature water-gas shift. 

Anthocyanins can form complexes with metal ions such as tin, iron and aluminium. The formation of a complex, as expected, alters the colour, usually from red to blue. Complex formation can be minimised by adding a chelating agent such as citrate ions. Another problem with anthocyanins is the formation of complexes with proteins. This can lead to precipitation in extreme cases. This problem is normally minimised by careful selection of the anthocyanin. 

Higuchi, K., Saitoh, T. and Hiraide, M. (2002). Selective uptake of copper (II) ions in water by chelating agent-impregnated liposomes, Bunseki Kagaku, 51, 745-749. 

In addition to solvents and diluents, formulations may contain emulsifiers, dispersants, chelating agents, thickeners, defoamers, and more. The large number and variety of each type makes selecting the components for a formulation difficult and time consuming. 

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