PEEK Tubing and Fittings for HPLC: A Practical Selection Guide

A source-backed guide to selecting PEEK tubing and HPLC fittings by pressure, port geometry, internal diameter, solvent compatibility, and extra-column volume.

PEEK Tubing and Fittings for HPLC: A Practical Selection Guide Tubing and fittings determine how the column, injector, detector, and pump are physically connected. Treat them as part of the chromatographic flow path: a connection that is incompatible, poorly seated, or oversized for the method can affect pressure, dispersion, sample recovery, and serviceability. Selection must begin with the exact system pressure , port style , tubing OD and ID , solvent , and instrument documentation . Use pressure and connection geometry as the first gate Do not select a fitting by material name alone. Agilent notes that LC connection styles and pressure limits vary: its PEEK or polyketone fittings are described as finger-tight up to 400 bar for low-pressure positions, while other fitting designs address substantially higher pressures.[1] Similarly, a specific Restek PEEK hex-head fitting is rated to 5000 psi (350 bar) for 1/16 in. tubing on 10-32 ports.[2] These are product-specific examples, not a universal PEEK rating. | Check first | Record before selection | Reason | | --- | --- | --- | | Maximum operating pressure | Method and system pressure, including any pressure spikes | The tubing and every connection in the flow path must be rated for the application. | | Port and thread | Exact port format, such as 10-32, Swagelok-style, or metric M4 | Similar-looking fittings are not necessarily interchangeable.[1] | | Tubing dimensions | OD, ID, and required length | These values affect fit, pressure, gradient delay, and extra-column volume. | | Material | PEEK, stainless steel, or another documented material | Material selection must account for pressure, analyte interaction, and solvent compatibility. | Manage internal diameter and extra-column volume Restek’s HPLC/UHPLC guidance reco