Methods and devices are provided for reducing the concentration of low molecular weight compounds in a biological composition containing cells while substantially maintaining a desired biological activity of the biological composition. The device comprises highly porous adsorbent particles, and the adsorbent particles are immobilized by an inert matrix. The matrix containing the particles is contained in a housing, and the particles range in diameter from about 100 .mu.m to about 1500 .mu.m. The device can be used to adsorb and remove a pathogen-inactivating compounds from a biological composition such as a blood product.