scholarly journals Reactivities of Radiation-Protective Aminoalkylisothiuronium Salts. VI. Estimation of the Stability of N-Substituted Derivatives of 2-Aminoethylisothiuronium Salt from the Potentiometric Titration Curve

1970 ◽  
Vol 18 (2) ◽  
pp. 399-401 ◽  
Author(s):  
AKIRA HANAKI
Keyword(s):  
Potentiometric Titration ◽  
Titration Curve ◽  
Potentiometric Titration Curve ◽  
The Stability ◽  
Derivatives Of

Observation of Two-Step Neutralization in Conductivity and Potentiometric Titration Curve in Polymer Grafted Charged Colloidal Systems

2006 ◽  
Vol 39 (6) ◽  
pp. 2016-2020 ◽  
Author(s):  
Priti Sundar Mohanty ◽  
Tamotsu Harada ◽  
Kozo Matsumoto ◽  
Hideki Matsuoka
Keyword(s):  
Potentiometric Titration ◽  
Titration Curve ◽  
Potentiometric Titration Curve ◽  
Colloidal Systems

Binding of calcium and lead ions to carboxystarch prepared by action of nitrogen dioxide on native starch and its 2,3-dialdehyde derivatives

1986 ◽  
Vol 51 (6) ◽  
pp. 1340-1351 ◽  
Author(s):  
Rudolf Kohn ◽  
Karol Tihlárik
Keyword(s):  
Nitrogen Dioxide ◽  
Alkaline Medium ◽  
Binding Capacity ◽  
Lead Ions ◽  
Carbonyl Groups ◽  
Weakly Alkaline ◽  
Exchange Cations ◽  
Counter Ions ◽  
The Stability ◽  
Derivatives Of

The binding of calcium and lead ions to carboxy derivatives of starch prepared by allowing nitrogen dioxide to act on native maize starch (procedure A) and on starch 2,3-dialdehyde derivatives of degrees of oxidation DO(d.a.) ≥ 0.94 (procedure B) was studied. The carboxy group content of the samples in the H+ form was 4.6 - 12.1 mmol g-1. The effect of alkaline medium on the stability of the carboxy derivatives and on their ability to bind and exchange cations was examined. The Ca2+ → 2K+ exchange was evaluated in terms of the decrease in the electrostatic free enthalpy Δ(Gel/N)KCa, determined by alkalimetric potentiometric titrations, and the binding of Pb2+ ions was evaluated in terms of the activity of the Pb2+ counter-ions determined in suspensions of Pb salts of the carboxy derivatives by means of an ion specific electrode. The IR and CD spectra revealed that the carboxystarch preparations obtained by procedure A contained, in addition to free carboxy groups, a considerable amount of carbonyl groups. During the conversion of the latter groups to the former, even in a weakly alkaline medium, the carboxy derivatives undergo an appreciable degradation and lose, to a great extent, their ability to bind and exchange cations. Procedure B, on the other hand, leads to highly selective starch and amylose carboxy derivatives, exhibiting a small amount of carbonyl groups and featuring a relative stability towards alkaline medium; their binding capacity is as high as 12 milliequivalents of cations per g of sample.

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