Complex-Forming Reagent

After Sousa [226] and Vogtle [227] rediscovered the potential of fluorescent and chromogenic complex forming reagents in the context of modem supramolecular photochemistry ca. 35 years ago, the field of the rational development of analyte-responsive fluorescent reporters saw a tremendous boost and naturally branched out... 

Another method of avoiding the ion-exchanger regeneration stage uses complex-forming reagents. This method is based on creating the conditions where complexes can be formed only in one of the columns. As a result the stationary front is maintained due to the difference in sorbability of separated and auxiliary ions in one column and the difference in the stability of complexes in the other. 

In the pH-zone refining technique, a basic organic solution containing a complex-forming reagent, such as... 

C-10 Electrode Potentials in the Presence of Precipitation and Complex-Forming Reagents... 

Problems It is disrupted by high concentrations of complex-forming reagents (e.g., EDTA) and by ammonium sulfate N-acteyl-glucosamine, glycine, reducing materials such as glucose, DTT, or Sorbitol and a host of pharmaceuticals such as chlorpromazine, penicillin, and vitamin C (Marshall and Williams 1991). 

Acac is a strong complex-forming reagent, therefore, a part of the Ni catalyst is corroded and transformed (even up to 75%) into the solution as the [Ni(acac)2] complex. Saturation of Ni with hydrogen and also modification with TA diminishes the solubility of Ni and its ability to form complexes with acac. These facts support theoretical suggestions about the formation of the triple complex [Ni - Modifier - Substrate] on the surface of modified Ni catalyst as the reaction proceeds... 

As complex forming reagents that form water soluble complexes with Ag(I), ammonia NH, potassiiun thiocyanate KSCN, sodium trioxosulphidosulphate(VI) Na S O, ethanediamine-1,2 H N-CH -CH -NH, 2-aminoethanol H N-CH -CH -OH, and 3-(2-hydroxyethyl)-3-azapenthanediol-l,5 N(CH -CH -OH), were used. At the Dnst stage of given processing of Ag-GM obtained, conversion of Ag-GlM into Ag pe(CN) ]-GlM occurred, on the second stage, reduction of Ag [Fe(CN) ]-GlM with Sn(ll) from elemental silver took place. And so, peculiar re-precipitation of elemental silver into gelatin matrix occurred incidentally. 

TABLE 1 The maximal (D/D s) and values of Ag(I) complexes for various complex forming reagents. 

Complex fonning reagent Concentration of complex forming reagent in solution at which reaches (D/D, gl pf of Ag(I) complex having 1 2 composition... 

Ag(I) complex with complex forming reagent reduction proceeding on interface of phases GIM/solution. 

In the pH-zone refining technique, a basic organic solution containing a complex-forming reagent, such as DEHPA, is used as the stationary phase. After the sample solution is introduced into the column, metal ions stay close to the sharp pH-border region in the small-bore... 

EDTA Ethylene diamine tetra acetic add (complex forming reagent)... 

Fig. 50. Polarometric titration, an insoluble salt titrated with a complex-forming reagent.

A similar titration curve (Fig. 50) is observed, when a suspension of lead tannate is titrated tvith dilute nitric acid in 20 per cent ethanol. By measuring the limiting current, lead can be determined in this complex. In a similar way insoluble precipitates can be analysed after the addition of complex-forming reagents, e.g. 

Monazite sample (1 g) was dissolved by heating with a mixture of H2SO4 and HF (1 1) with small content of HNO3. The solution was boiled until SO3 vapor appeared. The rare earth elements were separated from the matrix by extraction with 0.2 M diantipyrilmethane (a complex-forming reagent) solution in chloroform at pH 5 in the presence of 5.0M ammonium nitrate solution. The extraction was repeated and the combined extract was evaporated to dryness. The residue was dissolved in propanol saturated with NaCl and a 0.5 pi aliquot was spotted on TLC plate. After separation the rate earths were detected by spraying plates with a 0.1% arsenazo III solution (164). 

The effect of complex-forming reagents on the corrosion of metals was discussed in detail by Kuznetsov (1996). Complex formation plays an important role in the elementary act of metal dissolution. Thus metal cations passing into an electrolyte are always associated with solvent molecules, counter ions, or other components having free electron pairs. Many complexing agents, such as phosphonates, being easily soluble, can form complexes of various composition and may be not only mono- but also polynuclear. The latter are usually of low solubility and their formation can inhibit metal dissolution. Therefore adequate interpretation of the inhibition properties of phosphonates requires the study of the influence of complex formation on the inhibition effect of phosphonate based inhibitor compositions. 

Complex forming reagent, aqueous, buffered 1 x 10 M Zn(N03>2/l x 10 M fNH4] [hedtc]. Chromatographic solvent, 40% methanol/60% water (buffer). Flow rate, 0.8 ml min . Detection potential +0.9 V vs Ag/AgCl. Altex Cig Spherisorb Column. Temperature, 18°C. Data taken from reference [12]. 

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