Abstract: A filter comprises a nonporous support member open at one end and a porous disc rigidly secured to the support member at an opposite, preferably smaller, end. The disc may be formed from fibers preferably having a thickness of approximately 0.5-50 micrometers, or it may be formed from a plurality of particles or beads retained by a pair of membranes. When the disc is relatively small such as approximately 1 millimeter in diameter, it may be pressed into a constricted end of the support member. When the disc has an increased diameter, it may be rigidly supported by a retainer preferably made from a mesh material and welded to the support member. For even larger disc sizes, the disc may be supported between two (2) retainers preferably welded to the support member. A plurality of receptacles may be disposed in a tray to, serve as the filters, or receive the filters. The fluid may be introduced into, and retained in, the support members and discs by capillary action.