Syringe filter selection guide for HPLC and UHPLC
Updated
Filtering samples before injection prevents premature column clogging and pressure build-up, and filtering mobile phases protects instrument components as well[1]. Picking the right filter comes down to three choices: pore size, membrane and diameter.
1. Pore size: 0.45 µm or 0.2 µm
For HPLC, filtration through a 0.45 µm membrane is sufficient unless the column is packed with small particles such as sub-2 µm UHPLC packings, in which case a 0.2 µm filter is needed[1]. Filters labelled 0.22 µm belong to the same fine-filtration class. Note that filters with the same nominal rating can differ in how efficiently they retain particles[1].
2. Membrane: match it to the sample solvent
- Hydrophilic PTFE — for aqueous or organic solutions; Millex hydrophilic PTFE is specified as low-extractable and suitable for UHPLC and LC-MS[3].
- Hydrophobic PTFE — for aggressive organic, highly basic or hot solutions; aqueous solutions only after pre-wetting with an alcohol[2].
- Nylon and regenerated cellulose (RC) — widely used general-purpose membranes for aqueous and many organic samples; check the manufacturer's compatibility chart for your solvent.
- PVDF and PES — commonly chosen when low protein binding matters.
3. Diameter: match it to the volume
13 mm filters suit the small volumes that go into autosampler vials; 25 mm filters handle larger volumes. 47 mm membranes go into a filter holder for mobile-phase filtration.
Syringe filters in the catalog
Membrane filters for mobile phases
| Product | Part number | Membrane | Pore size | Diameter | Pack size | Price |
|---|---|---|---|---|---|---|
| Sartorius Cellulose Nitrate Membrane Filter, 47 mm, 0.45 µm (100/pk) | 11306--47------N | Cellulose nitrate | 0.45 µm | 47 mm | 100 | $134.09 USD |
| Dissolution Accessories Nylon Membrane Filter, 47 mm, 0.45 µm, Hydrophilic (200/pk) | PSMDC-NY47-045-0200 | Nylon | 0.45 µm | 47 mm | 200 | $104.64 USD |
Filtered samples go into clean vials: see the autosampler vial size & compatibility guide. For column protection also see choosing a guard column. Browse all syringe & membrane filters.
Frequently asked questions
Is a 0.45 µm syringe filter enough for HPLC?
For columns with conventional particle sizes, filtration through a 0.45 µm membrane is generally sufficient. Columns packed with sub-2 µm particles (UHPLC) are more prone to clogging and call for a 0.2 µm filter.
Can hydrophobic PTFE filters be used for aqueous samples?
Hydrophobic PTFE is intended for aggressive organic solvents; manufacturers note it can filter aqueous solutions only after pre-wetting with an alcohol. For aqueous or mixed samples choose hydrophilic PTFE, nylon or regenerated cellulose.
Which syringe filter diameter should I choose?
Choose by sample volume: 13 mm filters suit small volumes typical of autosampler vials, 25 mm filters handle larger volumes with less back-pressure. 47 mm membranes are used in filter holders for mobile phases.
Sources
- Merck / Sigma-Aldrich: The Importance of Filtration in Optimizing (U)HPLC and LC-MS Performance
- Thermo Fisher Scientific: Titan3 PTFE (Hydrophobic) Syringe Filters – product information
- Merck / Sigma-Aldrich: Millex hydrophilic PTFE syringe filter – product information
Specifications in the tables come from each product's source listing (linked on its product page). Always confirm critical limits against the manufacturer's current documentation.