PEEK-encased frits surround the frit with a ring of PEEK, reducing the actual porous surface to the ID of an HPLC column.
The compressed PEEK ring forms a seal between the bottom of the fitting and the column end, preventing the mobile phase and the sample from entering the previously accessible poorly swept areas.
Titanium frits
Intended for HPLC columns with IDs of 3.2 and 4.6 mm. Titanium is biocompatible and recommended for protein analysis.
Polyethylene frits
Polyethylene frits are a competitively priced biocompatible alternative to titanium and are completely metal free.