How to find the right Chromatography Fittings AI guide
Written by an AI model from its trained knowledge.
What the AI looks for in Chromatography Fittings
- Port thread and seat style
- Use 10-32 coned fittings for HPLC/UHPLC ports and 1/4-28 flat-bottom fittings for low-pressure FPLC and solvent lines; M6 is a common metric low-pressure alternative. Coned and flat-bottom fittings are not interchangeable, and a wrong seat style will not seal or will crack the port.
- Ferrule stem depth match
- Match the ferrule or stem length to the port maker's geometry (for example Waters, Parker or Valco), or use adjustable-depth finger-tight fittings. A mismatched depth leaves a void that adds dead volume and broadens peaks, or stops the tube short so the fitting leaks.
- Tubing outer diameter
- Most HPLC systems use 1/16 in OD tubing, nano/capillary LC often uses 1/32 in or 360 µm, and GC packed columns use 1/8 in or 1/4 in. The fitting, ferrule and tube OD must all match. The ferrule bore must grip the exact tube OD, and near-sizes leak or crush the tube.
- Pressure rating vs system
- Conventional HPLC runs up to about 400 bar, while UHPLC can exceed 1000 bar. Use fittings rated explicitly for UHPLC on those systems. Standard PEEK finger-tight fittings slip or leak at UHPLC pressures.
- Material and solvent compatibility
- Use PEEK or bioinert fittings for metal-sensitive or biological samples and stainless steel for high pressure. Keep PEEK away from concentrated nitric or sulfuric acid, and be cautious with THF, DMSO and methylene chloride on PEEK tubing. The wrong material corrodes, swells, or leaches metal ions into sensitive analytes.
- GC ferrule material
- Graphite seals well and tolerates high temperature. Vespel/graphite composite suits GC-MS connections but shrinks after thermal cycling and needs re-tightening. Ferrule choice controls leaks, contamination at the detector and how often you re-tighten.
Brands that matter
- IDEX Health & Science (Upchurch): Broadest range of HPLC finger-tight, PEEK and adapter fittings.
- VICI Valco: Zero-dead-volume stainless fittings and valve-matched ferrules.
- Swagelok: Instrument-grade compression fittings widely used on GC gas lines.
- Restek: GC ferrules, column nuts and capillary connectors.
- Agilent: OEM fittings for Agilent LC and GC, including UHPLC-rated connections.
- Thermo Fisher Scientific: Viper fingertight UHPLC connections for Thermo systems.
- Waters: OEM fittings sized for Waters port geometry.
What to avoid
- Reusing a swaged stainless ferrule in a port from a different manufacturer.
- Over-tightening PEEK fittings, which deforms the ferrule and cracks ports.
- Mixing nut and ferrule components from different brands on compression fittings.
- Using standard PEEK finger-tight fittings on UHPLC systems.
Questions
Why do my peaks tail after I replaced a fitting?
The ferrule depth probably does not match the port, which leaves a dead-volume void. Re-make the connection with a depth-matched or adjustable fitting.
Can I use a 1/4-28 fitting in a 10-32 port?
No. Both the threads and the seat geometry differ. Use an adapter union if you need to join the two systems.