HPLC fittings, ferrules and tubing: a selection guide
Updated
Leaks, peak tailing from dead volume and blocked columns often trace back to a fitting, a length of tubing or a missing filter. This guide covers the parts in the fittings, tubing & inline filters category and when to use each.
1. Identify the port and tubing
Most column and module connections are 10-32 coned ports with 1/16" OD tubing. Some valves and low-pressure lines use 1/4-28 flat-bottom ports, for which flangeless fittings such as IDEX Upchurch XP-235X Short Flangeless PEEK Fitting, 1/4-28 Flat-Bottom, 1/16" OD (10/pk) (XP-235X) are used.
2. Choose the fitting type
- One-piece fingertight — fast, tool-free and reusable: IDEX Upchurch F-120 One-Piece Fingertight PEEK Fitting, 10-32 Coned, 1/16" OD (
F-120). - Two-piece fingertight — separate nut and ferrule for a firmer grip: IDEX Upchurch F-300X Two-Piece Fingertight Fitting, 10-32 Coned, 1/16" OD (10/pk) (
F-300X) with replacement IDEX Upchurch F-142X PEEK Fingertight Ferrules, 10-32 Coned, 1/16" OD (10/pk) (F-142X). - High-pressure PEEK — for UHPLC, use fittings rated for your operating pressure, such as VICI Jour PEEK-HT One-Piece UHPLC Fitting, 10-32, up to 1000 bar (5/pk) (
JR-55031-5). - Stainless steel ferrules — permanent, high-pressure seals on steel tubing: VICI Valco ZF1S6 Stainless Steel Ferrules, 1/16" (10/pk) (
ZF1S6-10).
Shimadzu users can also use genuine EXP hand-tight fittings, listed in the Shimadzu consumables guide.
3. Choose the tubing
PEEK tubing is colour-coded by inner diameter. Narrow-ID tubing such as Applied Research Europe PEEK Tubing, 1/16" OD x 0.007" (0.18 mm) ID, Yellow Stripe, HPLC Grade, 3 m (47305-07-3M) keeps extra-column volume low for UHPLC and LC-MS; VICI Jour PEEK Tubing, 1/16" OD x 0.25 mm ID, Blue Stripe, 3 m (JR-T-6001-M3) is a common general-purpose size. Cut PEEK tubing square with a proper cutter so the end seats flat in the port.
4. Add inline and inlet filters
A precolumn inline filter catches particles before they reach the column frit: IDEX Upchurch A-318 Precolumn Filter, 0.5 µm, 0.84 µL Swept Volume (A-318), IDEX Upchurch A-316 Precolumn Filter, 0.5 µm, 1.3 µL Swept Volume (A-316) or, for Agilent RRLC/UHPLC systems, Agilent Inline Filter, Stainless Steel, 0.2 µm, 2.1 mm (RRLC) (5067-1551) with replacement Agilent 1290 Inline Filter Replacement Frits, 0.3 µm, Stainless Steel (5/pk) (5023-0271). On the solvent side, an inlet filter on each line protects the pump: IDEX Upchurch A-302A Solvent Inlet Filter, 10 µm, for 1/8" OD Tubing (A-302A) or Waters Solvent Inlet Filter, 10 µm, 1/8" OD (PSL613578).
Combine filters with a guard cartridge (guard column guide) and filtered samples (syringe filters) for the longest column life.
Frequently asked questions
What thread do most HPLC fittings use?
Most analytical HPLC connections use 10-32 coned ports with 1/16" OD tubing. Some valves and low-pressure connections use 1/4-28 flat-bottom fittings instead, so check the port type before ordering.
Can I reuse fingertight PEEK fittings?
Yes, fingertight PEEK fittings are designed to be reused and moved between ports. Stainless steel ferrules are swaged onto the tubing permanently and should stay with that tubing and port depth.
Why does tubing inner diameter matter?
Every microlitre of tubing volume after the injector broadens peaks. Narrow-ID tubing reduces extra-column volume, which matters most for UHPLC and 2.1 mm ID columns; wider ID tubing is fine on solvent lines where back-pressure is the bigger concern.