emerging in the order Li
+ > Na
+ > K
+ . Alkaline earth metal ions can be eluted
with 1.2 M ammonium lactate in a Dowex-50 column, emerging in the order
Ca
2+ > Sr
2+ > Ba
2+ (Rieman 2013).
E. Gel Column Chromatography
In gel column chromatography, a molecular sieve is used for the stationary phase.
These include Sephadex, polyacrylamide, and agarose gel. Being hydrophilic, they
absorb water and may swell. When specimen molecules are larger than the maximum pore size in the expanded gel, they can pass through the gel molecules and
emerge easily from the column through spaces in the stationary phase molecules.
Smaller molecules pass through openings in the gel particles, emerging at different
rates according to their size and shape. In other words, molecules take longer to
pass and are extracted more slowly the smaller they are (Fig. 10.8) (Lathe and
Ruthven 1956).
Gels used for the separation and refinement of natural marine substances include
Sephadex G or Sephadex LH, which are made from dextran and its derivatives and
are among the most commonly used gells; biogel P, which is the chief gel made
with polyacrylamide and its derivatives; and agarose, cross linkage agarose,
polyvinyl, cellulose, and polystyrene varieties. Sephadex G, Sephadex LH-20, and
biogel P are chiefly used for the separation and refinement of natural substances.
Sephadex is mainly used for isolating proteins and tends to absorb large amounts of
water due to the strong polarity resulting from hydroxyl groups on the polysaccharides and large polymer chains. The characteristics of gels are the result of their
capacity for reabsorbing water and expanding.
Fig. 10.7 Ion exchange
chromatography for proteins
360
10 Marine Natural Substances
+ > Na
+ > K
+ . Alkaline earth metal ions can be eluted
with 1.2 M ammonium lactate in a Dowex-50 column, emerging in the order
Ca
2+ > Sr
2+ > Ba
2+ (Rieman 2013).
E. Gel Column Chromatography
In gel column chromatography, a molecular sieve is used for the stationary phase.
These include Sephadex, polyacrylamide, and agarose gel. Being hydrophilic, they
absorb water and may swell. When specimen molecules are larger than the maximum pore size in the expanded gel, they can pass through the gel molecules and
emerge easily from the column through spaces in the stationary phase molecules.
Smaller molecules pass through openings in the gel particles, emerging at different
rates according to their size and shape. In other words, molecules take longer to
pass and are extracted more slowly the smaller they are (Fig. 10.8) (Lathe and
Ruthven 1956).
Gels used for the separation and refinement of natural marine substances include
Sephadex G or Sephadex LH, which are made from dextran and its derivatives and
are among the most commonly used gells; biogel P, which is the chief gel made
with polyacrylamide and its derivatives; and agarose, cross linkage agarose,
polyvinyl, cellulose, and polystyrene varieties. Sephadex G, Sephadex LH-20, and
biogel P are chiefly used for the separation and refinement of natural substances.
Sephadex is mainly used for isolating proteins and tends to absorb large amounts of
water due to the strong polarity resulting from hydroxyl groups on the polysaccharides and large polymer chains. The characteristics of gels are the result of their
capacity for reabsorbing water and expanding.
Fig. 10.7 Ion exchange
chromatography for proteins
360
10 Marine Natural Substances