STEROID ADSORPTION TO GEL FILTRATION MEDIA, AND ITS PREVENTION BY SERUM

1. 1. The adsorption of testosterone, deoxycortisol, cortisol and aldosterone to Sephadex G-50 and G-25 and to Bio-Gel P-10 has been studied. Linear, reversible adsorption (delay in elution) occurred at physiological ionic strength. The degree of adsorption of these steroids decreased in the order given above; gel partition co-efficients (Kav) ranged from 1.00 for aldosterone on Sephadex G-50 to 2.02 for deoxycorticosterone on Sephadex G-25. 2. 2. A new finding was that steroid adsorption to Sephadex G-50 was prevented by serum or plasma. When the steroids were applied to Sephadex G-50 in serum, the free peaks were eluted at the salt volume of the columns, and were not delayed. However, serum or plasma had no effect upon free steroid elution volume on Bio-Gel P-10 columns, possibly because of the different nature of the adsorptive sites in this gel. Possible mechanisms for the shift of free steroid peaks on Sephadex G-50 in the presence of serum or plasma are discussed; it seems unlikely to be due to protein binding on the evidence reported. 3. 3. In practice, it is desirable to carry out gel filtration of steroids in serum or plasma on Sephadex G-50, to prevent their adsorption to the gel column. © 1969.