Precision of quantitative electron spin resonance using copper(II) bound to ion-exchange resins

1977 ◽  
Vol 49 (2) ◽  
pp. 250-255 ◽  
Author(s):  
Doris C. Warren ◽  
J. M. Fitzgerald
Keyword(s):  
Electron Spin Resonance ◽  
Ion Exchange ◽  
Electron Spin ◽  
Ion Exchange Resins ◽  
Spin Resonance ◽  
Exchange Resins

MNII-FULVIC ACID COMPLEXING EQUILIBRIUM MEASUREMENTS BY ELECTRON SPIN RESONANCE SPECTROMETRY

1977 ◽  
Vol 57 (1) ◽  
pp. 47-53 ◽  
Author(s):  
D. S. GAMBLE ◽  
M. SCHNITZER ◽  
D. S. SKINNER
Keyword(s):  
Electron Spin Resonance ◽  
Ion Exchange ◽  
Fulvic Acid ◽  
Electron Spin ◽  
Weighted Average ◽  
Outer Sphere ◽  
Water Soluble ◽  
Exchange Method ◽  
Spin Resonance ◽  
Esr Spectrometry

Electron spin resonance (ESR) spectrometry was used to determine weighted average equilibrium functions [Formula: see text] for water-soluble complexes formed between fulvic acid and divalent manganese. [Formula: see text] values ranged from 0.2 × 10−2 (at pH 6.15) to 0.5 × 10−3 (at pH 6.45) and were in excellent agreement with [Formula: see text] values determined previously for Mn–fulvic acid complexes by an ion-exchange method. The ESR method was found to be more sensitive, convenient and faster than the ion exchange procedure. From the data presented in this and in earlier publications it appears that MnII is bound simultaneously electrostatically and by hydrogen-bonding as Mn(OH2)62+ to fulvic acid donor groups in outer sphere complexing sites. These complexes are likely to be unsymmetrical.

Embedding Procedure for Water Swollen Samples

1970 ◽  
Vol 28 ◽  
pp. 504-505
Author(s):  
Ann M. Thomas ◽  
Virginia Shemeley
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Ion Exchange ◽  
Structural Changes ◽  
Cross Linking ◽  
Ion Exchange Resins ◽  
Transmission Electron ◽  
First Pass ◽  
Exchange Resins

Those samples which swell rapidly when exposed to water are, at best, difficult to section for transmission electron microscopy. Some materials literally burst out of the embedding block with the first pass by the knife, and even the most rapid cutting cycle produces sections of limited value. Many ion exchange resins swell in water; some undergo irreversible structural changes when dried. We developed our embedding procedure to handle this type of sample, but it should be applicable to many materials that present similar sectioning difficulties.The purpose of our embedding procedure is to build up a cross-linking network throughout the sample, while it is in a water swollen state. Our procedure was suggested to us by the work of Rosenberg, where he mentioned the formation of a tridimensional structure by the polymerization of the GMA biproduct, triglycol dimethacrylate.

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