Complex-forming buffers

Volatile or complex-forming buffers (special additives)... 

Cobalt in steel Discussion. An alternative, but less sensitive, method utilises 2-nitroso-l-naphthol, and this can be used for the determination of cobalt in steel. The pink cobalt(III) complex is formed in a citrate medium at pH 2.5-5. Citrate serves as a buffer, prevents the precipitation of metallic hydroxides, and complexes iron(III) so that it does not form an extractable nitrosonaphtholate complex. The cobalt complex forms slowly (ca 30 minutes) and is extracted with chloroform. 

We have studied stoichiometry of complex formation between DNA and PLL and found that the complexes formed in low-salt-buffer solutions are of a 1 1 charge ratio [92]. The same 1 1 stoichiometry was found experimentally for DNA complexed with other synthetic polycations of different nature in low-salt aqueous solutions [such as poly (diallyldimethylammonium chloride), poly(dimethyhmino)ethylene(dimethylimino)ethy-lene-l,4-dimethylphenylmethyl ene dichloride, andpoly(4-vinyl-A-methylpyridinium bromide)] [93]. 

Immediately after irradiation, stop the reaction by the addition of 7 pi of 4 X SDS electrophoresis loading buffer or the equivalent (with a high concentration of reducing agent present) 0.2M Tris, 8 percent SDS, 2.88M P-mercaptoethanol, 40 percent glycerol, 0.4 percent xylene cyanol, 0.4 percent bromophenol blue. Heat the sample at 95°C for 5 minutes and analyze the complexes formed by electrophoresis. 

Consequently, the research work of Hara s group continued focusing on the improvement of protein determination using CE combined with online CL detection. By replacing EY by the Rhodamine B isothiocyanate (RITC) dye in the binary complexes formed with the proteins BSA or human serum albumin (HSA) and using a different imidazole buffer solution of pH 6, the sensitivity was increased [72], However, best detection limits for these determinations were found employing the tetramethylrhodamine isothiocyanate isomer (TRITC) dye, left for 4 h with a standard solution of BSA in acetonitrile followed by introduction into the capillary. For BSA, a detection limit of 6 nM was reached [73],... 

The most controversial issue is the number and exact stoichiometries of the iron(III)-sulfito complexes formed under different experimental conditions. Earlier, van Eldik and co-workers reported the formation of a series of [Fe(SO ) ]3-2" (n = to 3) complexes and the [Fe(S03)(0H)] complex (89,91,92). The stability constants of these species were determined by evaluating time resolved rapid-scan spectra obtained from the sub-second to several minutes time domain. The cis-trans isomerization of the complexes was also considered, under feasible circumstances. In contrast, Betterton interpreted his results assuming the formation and linkage isomerization of a single complex, [Fe(SC>3)]+ (93). In agreement with the latter results, Conklin and Hoffmann also found evidence only for the formation of a mono-complex (94). However, their results were criticized on the basis that the experiments were made in 1.0 M formic acid/formate buffer where iron(III) existed mainly as formato complex(es). Although these reactions could interfere with the formation of the sulfito complex, they were not considered in the evaluation of the results (95). Finally, van Eldik and co-workers re-examined the complex-formation reactions and presented additional data in support of... 

From a manufacturing standpoint, preparation of the double-antibody immune complex can be very labor intensive. For optimal manufacturability and analytical performance of this system, it is important to have a secondary antibody with a moderate to high affinity so that a mixture of immune complexes of appropriate molecular weights is formed. The molecular size and shape of complexes formed depends on a number of parameters, such as temperature, buffer characteristics, ionic strength and the presence of other solution components such as detergents. These conditions must be carefully controlled or else species of very high molecular weight could be formed due to temperature or buffer interactions. Lot-to-lot variability in the primary and secondary antibody raw materials can also affect the solid phase performance if not properly controlled. 

Figure 4 shows CD spectra of (a) the DNA-lipid complex in organic solution containing a small amount of water (CHCl3/Et0H/Fl20 =4 1 0.07, 790 mM of H2O), and (b) native DNA in an aqueous buffer solution (20 mM NaCl, 10 mM Tris, pH 7.8). The DNA-lipid complex shows a positive Cotton effect at 270 nm and a negative Cotton effect at 245 nm similar to native DNA in aqueous solution, which indicates the B-form structure for the DNA strands [11]. Thus, the DNA-lipid complex forms a double helical B-form... 

Aresta (54) has investigated the platinum complexes formed with o-allylphenol and o-allylthiophenol. The phenolic ligand reacts with the PtCl4 ion (in a suitable acetate buffer) to form the chelate complex shown in Fig. 40. The coordinated double bonds of this compound are successively replaced by two equivalents of pyridine. 

Affinity capillary electrophoresis is an approach where the migration pattern of interacting molecules are used to identify and quantify specific binding and estimate binding constants. Therefore, the solutes are first separated conventionally by CE. In a second run, the run buffer is doped with a specific complex-forming substance, and the change in the retention time... 

The analyte is loaded onto the gel in a buffer at ca pH 7.0 and the complex formed can then be broken down using a mildly acidic eluent such as 0.1 M acetic acid. This type of extraction has been applied to the determination of dopamine, adrenaline and noradrenaline in plasma and to the determination of the extent of reaction of glucose with serum albumin as a measure of glucose fluctuations with time in diabetics. 

Coordination of flexible amidic structures to the palladium ion resulted in the formation of a rigid hydrophobic cavity of 61 [82]. This self-assembly takes place in water, and aromatic carboxylates are recognized in it. It was found using NMR titration in D20 (pD=8.5, borate buffer). The structure of the complex formed is shown schematically in Fig. 4. It is apparent that cooperative binding of both carboxylates is essential for the stability of the complex formed nevertheless, the enantioselection of carboxylates is only very weak (Table 5). 

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