Fractionation of Polyacrylamide by Gel Permeation Chromatography in Water

Example 3.10 Fractionation of Polyacrylamide by Gel Permeation Chromatography in Water 

Safety precautions Before this experiment is carried out. Sect. 2.2.5 must be read as well as the material safety data sheets (MSDS) for aU chemicals and products used. 

A solution of 250 mg of poly(acrylamide) from Example 3.9 in 25 ml of distilled water is introduced at the top of the coluirm. At the same time the collection of the 

The fractions collected are each run dropwise into 100 ml of stirred methanol to which two drops of concentrated hydrochloric acid have been added. Turbidity or precipitation will be observed from about the 6th fraction to about the 20th fraction. The precipitated fractions are filtered off, washed with methanol and dried to constant weight in vacuum at 20°C. For each fraction the viscosity is measured in water at 25°C using a capillary viscometer (capillary diameter 0.35 mm) and at as high a concentration as possible (10 gA) in order to minimize errors. The hmiting viscosity number, and hence the molecular weight, is estimated (see Sect. 2.3.3.3). Adjacent fractions for which there may be insufficient material for a viscosity measurement, can be combined where necessary. 

After the fractionation, the amount of the individual fractions in mg is plotted against the elution volume. One can test whether there has been any loss of polymer by comparing the total mass of all the fractions with the initial amount the loss should not be more than 3%. 

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