Minisart SRP syringe filters with a clean and chemically inert PTFE membrane. The units are ready-to-use and allow for simple, rapid and reliable ultracleaning of small volume samples for HPLC or GC analysis, which require an even more chemical resistant unit than Minisart RC, e.g. for solvents such as acetone, dimethylformamide and DMSO, or for aggressive aqueous liquids.