The Millipore Omnipore™ membrane is hydrophilic PTFE membrane filter that is chemically inert and compatible with virtually all reagent chemicals, solvents, acids, and alkaline solutions. Omnipore™ PTFE membrane filters are ideal for clarifying acids, alkaline or basic solutions and laboratory solvents. Millipore Omnipore™ PTFE membrane filters are especially efficient for HPLC solvent filtration and preparation. Filter Color: White. Filter Surface Plain & Smooth.