PEEK Fitting Set — Sales and Instrument Support

Set of finger-tight PEEK fittings for HPLC flow-path connections. PEEK (polyether ether ketone) gives a metal-free, bio-inert flow path and can be made and remade by hand without a spanner, which is why it is the default for solvent-side and post-column plumbing.

Two limits are worth knowing before fitting them. PEEK fittings are pressure rated well below stainless steel - commonly in the region of 5,000 psi depending on the design - and PEEK is swollen or attacked by concentrated nitric and sulfuric acids and, on prolonged contact, by tetrahydrofuran and methylene chloride. Stainless steel is the correct choice in those cases.

Dead volume is the real risk

A fitting's ferrule sets how far the tubing stub protrudes into the receiving port. If the stub is too short for that port, the gap left behind is dead volume, and dead volume shows up in the chromatogram as tailing peaks, broadened early peaks and lost resolution rather than as a leak. Ports differ between manufacturers, so a fitting that seals perfectly can still cost you plate count. Seat the tubing firmly against the bottom of the port while tightening the first time.