Non sterile Whatman GD/X Syringe Filters combine a polypropylene housing, highefficiency Whatman GMF 150 and GF/F prefilter media, and one of the following membrane materials: Polyethersulfone (PES) for serum, plasma and tissue culture Polyvinylidene difluoride (PVDF) for HPLC Cellulose acetate for biological solutions Borosilicate glass microfiber Whatman GD/X Syringe Filters are highviscosity filters that incorporate a prefilter to enable filtration of viscous, dense or otherwise hardtofilter material with high solids content as in environmental and food analysis samples. High viscosity filter enables filtration of “difficult to filter” samples The prefilter contains a highefficiency borosilicate glass filtration stack that will retain fine particles down to 0.7 μm, allowing difficult sample filtration with less hand force. It reduces the need for multiple syringe filters by processing three to seven times more sample volume than syringe filters without prefilters. The filters can be autoclaved.