Polydextran gels

Many other substrates have been used for IEC in addition to the polystyrenes. Some are natural products like cellulose, often crosslinked for added rigidity, and others are manufactured like polydextran gels. Most of them can only be used at low pressures, like the polystyrenes just discussed. 

Methylamino-5-(l-methylalIylamino)-l,3,4-thiadiazoIe is an oxidation product of methallibure, a veterinary oestrus regulator. Separation can be achieved by chromatography on alkylated polydextran gel and elution with mixed organic solvents. Metal salts can be removed by complexation with diphenylthiocarbazone (70JPS835). 

Porath and Flodin Cross-linked polydextrans—Gel filtration... 

In addition to the classical column packing materials (silica gel, alumina, celite), other widely used columns are of the polydextran gel type for the fractionation of the polar steroids, Sephadex LH-20, and for the less polar steroid compounds its hydro-xyalkyl derivative, Lipidex. The use of ion exchange columns (e.g., DEAE-Sephadex A-25, Amberlite XAD-2) is also widespread. High selectivity is attainable with immunoaffinity chromatography, where antibodies are immobilized on chemically modified agarose gel and filled in columns. For the solid-phase... 

Kinetic studies of porcine pancreatic a-amylase derivatized with 5,5 -dithiobis-(2-nitrobenzoic acid) have shown that P is decreased by a factor of four whereas K is unchanged. The derivatized enzyme binds to polydextran gel as effectively as the native enzyme. 

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