The separation of substances and estimation of their relative molecular sizes by the use of columns of starch in water

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Abstract
From columns of potato starch in buffer neutral molecules were eluted in the descending order of their molecular weights. There was good resolution of substances in the molecular weight range of 100 to 1000. The behavior of small charged molecules was complicated by ion-exchange effects which could be minimized by the addition of salt. Large molecules remained outside untreated starch grains. Starch which has been swollen by warming in water was permeable to large molecules, and in columns separated them in the range of molecular weights 150,000 to 1300. The possibility of determining molecular weights with these columns is discussed. Values of 6000 for insulin and 35,000 for ox myoglobin were obtained. It is suggested that columns of starch in water form a new type of partition system in which the volume of the stationary phase is determined for each substance by the depth to which it can penetrate the starch granules.