Whatman GD/XP Syringe Filters are suitable for use with samples that require inorganic ion analysis, as levels of ion extractables have been minimized. GD/XP syringe filters contain a two-layer prefilter stack comprised of 20 µm and 5 µm polypropylene filters. A range of membrane options are available for the last stage of filtration, positioned below the prefilter stack.