What is diatomaceous earth?

Diatomaceous earth is an adsorbent that works like a sponge for aqueous samples and is commonly used for SLE or supported liquid extraction (i.e. Agilent Chem Elut cartridges or hydromatrix media).  When an aqueous sample is applied to it, the entire sample is absorbed by the diatomaceous earth material.  Elution of analytes is carried out using a water immiscible solvent, such as dichloromethane, ethyl acetate, etc.