Purification of biological products by constrained cohydration chromatography

A method for purification of a hydrated target species of biological origin in a sample comprising the steps of contacting the sample with a hydrated surface of an undissolved material and contacting the sample with a constraining agent in an amount sufficient to cause more than 50% to substantially all of the target species to be retained at the hydrated surface of the undissolved material, wherein

• (i) the undissolved material comprises particles,
• (ii) a surface of the particles includes charged moieties,
• (iii) the target species is retained exclusively by constrained cohydration under conditions providing a substantial absence of a direct chemical interaction between the target species and the hydrated surface, and
• (iv) the conditions that provide the substantial absence of a direct chemical interaction comprise pH, conductivity and salt concentration of buffers delivered to a column of the particles, wherein said conditions discourage direct interaction between the hydrated target species and the charged moieties, and wherein the particles are optionally a convective chromatography material.