a three - dimensional microporous polymer network material , or monolith , cast - to - shape in a microchannel . the polymer monolith , produced by a phase separation process , is capable of trapping and retaining charged protein species from a mixture of charged and uncharged species under the influence of an applied electric field . the retained charged protein species are released from the porous polymer monolith by a pressure driven flow in the substantial absence of the electric field . the pressure driven flow is independent of direction and thus neither means to reverse fluid flow nor a multi - directional flow field is required , a single flow through the porous polymer monolith can be employed , in contrast to prior art systems . the monolithic polymer material produced by the invention can function as a chromatographic medium . moreover , by virtue of its ability to retain charged protein species and quantitatively release the retained species the porous polymer monolith can serve as a means for concentrating charged protein species from , for example , a dilute solution .