STATIC AND DYNAMIC STUDIES OF PROTEIN SORPTION BY POROUS ALKYLSILICA

Porous alkylsilicas are important stationary phases (sorbents) for separating proteins by high performance liquid chromatography and have great potential for large scale isolations. We have employed batch experiments, frontal chromatography, and surface energy measurement techniques to study the factors which influence protein sorption to these materials. Proteins such as bovine serum albumin are sorbed irreversibly from phosphate buffer at pH 7 and pH 2. Addition of alcohol at sufficient concentration to reduce the surface tension of the solvent to lesis than 34 ergs/cm 2 effected desorption at pH 2 but not at pH 7. Proteins were desorbed by solutions of nonionic surfactant at pH 7. The chain-lengths of alkyl groups on the silica had little influence on sorption isotherms which, in the batch studies, were of the general Langmuir shape. The isotherms derived fron the frontal experiments were indicative of two-stage desorption process.