Boric acid point group

In the first section, the studies on the complex which have been made by many authors from various points of view were reviewed. Most of the studies on the complex have been made in aqueous PVA-Iodine-KI solutions with Boric acid. Our group, however, has been interested in the structural studies of the complex formed in PVA films. In Sect. 1, the importance of the structural study on the complex, as well as the problems and the intention of our studies were described. 

According to von Vargha the points of attachment of the first isopropylidene group in D-mannitol can be altered by the use of boric acid. Ordinarily the 3,4 isomer is obtained. However, in the presence of boric acid a l,2-isopropylidene-4,5-monoborate is formed which is readily decomposed to 1,2-isopropylidene-D-mannitol. 

FIG. 23 Phase diagram of bovine serum albumin/HMPA mixtures in 300 mM NaN03, 20 mM boric acid-NaOH buffer pH 8.7. The HMPA is a poly(acrylic acid) of Mw 150,000 grafted by 3 mol% of C18 groups. Cloud-points were observed by eye after a one-night incubation period of the mixtures. In the demixed samples, the upper phase was highly dilute (<0.5% protein and 0.2% polymer) and the bottom phase contained the polymer/protein complex (concentrations >0.8% polymer and >1% protein). 

To a limited extent, sodium tetraborate is also suited for gradient elution, because boric acid as the suppression product is only weakly dissociated. As an alternative to carbonate/bicarbonate systems, amino acids (a-aminocarboxylic acids) may be used as an eluent [90,91]. Their dissociation behavior is depicted in Figure 3.102. At alkaline pH, amino acids exist in the anionic form due to the dissociation of the carboxyl group and thus may act as an eluent ion. The product of the suppressor reaction is the zwitterionic form with a correspondingly low background conductance. This depends on the isoelectric point, pi, of the amino acid. 

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