Ready-to-use, syringe-driven units designed for sterilizing and clarifying sterile solutions are available in 0.1, 0.22, 0.45 and 5.0μm pore sizes. Pricing and Availability. Merck Millex™-GP Syringe Filter, PES, 0.22 μm. Ideal for preparing 10–100mL samples prior to chromatography or other instrumental analyses.