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Cation‐exchange capacity of plant cell walls at neutral pH
Author(s) -
Allen Michael S.,
McBurney Michael I.,
Van Soest Peter J.
Publication year - 1985
Publication title -
journal of the science of food and agriculture
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.782
H-Index - 142
eISSN - 1097-0010
pISSN - 0022-5142
DOI - 10.1002/jsfa.2740361107
Subject(s) - praseodymium , neodymium , cation exchange capacity , chemistry , molar absorptivity , ion exchange , analytical chemistry (journal) , manganese , lanthanide , rare earth , hydroxide , inorganic chemistry , nuclear chemistry , ion , mineralogy , environmental chemistry , soil water , organic chemistry , laser , physics , environmental science , soil science , optics
A new method of measuring the cation‐exchange capacity (CEC) of plant materials was developed utilising the tripositive rare earth (RE) elements praseodymium (Pr) or neodymium (Nd). Unlike monovalent cations, the trivalent rare earths become tightly bound to fibre thus decreasing the variability involved with washing. Since the acetate complexes of the rare earths are soluble and relatively stable to hydroxide formation up to pH 7.0, this method can be used to measure CEC of plant materials over the pH range of the gastrointestinal tract. Furthermore, background levels of the RE elements are low in plant tissue. Trivalent Pr and Nd absorb in the visible region of the light spectrum and have the greatest absorptivity of the RE elements. Pr was selected over Nd for this method based upon the binding characteristics of the element. However, Nd may be used if interferences are encountered using Pr. The conditions chosen for optimal binding of Pr to plant materials are as follows: 0.5g samples soaked in 10ml of 0.10 M RE acetate, at pH 7.0, for 24h, at 39°C. Coefficients of variation were less than 3.6% for each RE‐feedstuff combination examined.