An apparatus for extracting an analyte from a liquid sample having a container with an entrance, an exit, and a passage therebetween for passage of a liquid sample containing an analyte, the container having a full diameter bed region and a reduced diameter bed region. The container includes a layered construction extending across the passage, having from top to bottom one or more of: (i) an upper flow distributor/support layer, (ii) an upper compression layer, (iii) an extraction layer of microparticulate extraction medium adjacent to the layer (ii), and (iv) a lower compression layer located adjacent to the extraction layer (iii), optionally including one or more air gap layers. At least some of the layers are located in the full diameter bed region, and some of the layers are located in the reduced diameter bed region. The apparatus may have a plurality of containers arranged in an array and/or in series so as to provide multi-stage filtration or extraction.