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RESEARCH PRODUCT

Gel permeation Chromatography in coiled columns

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Whereas in gas chromatography the use of coiled columns is the usual procedure, in liquid chromatography the use of straight columns is favoured. Bent columns give an additional contribution to peak spreading which is of greater importance in liquid chromatography than in gas chromatography owing to smaller diffusion coefficients. The low linear velocities of the mobile phase used in gel permeation chromatography enable conditions to be found where the additional contribution of bending to peak spreading is small. In the separation of oligomers, columns of 2-mm tube diameter and 20-cm coil diameter were used. With total lengths of 10 and 20 m, theoretical plate counts of ca. 70,000 and 150,000, respectively, could be obtained. The experimental conditions of columns filling, etc., are discussed. Examples are shown to demonstrate the potentialities of this technique. The main advantage is the low solvent requirement and the practicability. As predicted by theory, there is no advantage with respect to analysis time.