Solvent Filters and Inlet Filters

Tech Tip | Why Use an Inlet Solvent Filter?

An inlet solvent filter helps protect LC and UHPLC systems by removing particulate matter from the mobile phase before it reaches expensive pumps, check valves, mixers, injectors, and columns.

  • ▸ Filter particulate matter from solvent reservoirs. Use a 10 µm or 20 µm inlet filter for general particulate protection. A-309 and A-230A filters have a Bottom-of-the-Bottle™ design to help draw solvent to within 1/8" of the bottom of the solvent bottle.
  • ▸ Prevent sparging-related particulates from entering the mobile phase reservoir. A 2 µm filter is commonly used for this purpose and helps disperse sparging gas efficiently.
  • ▸ Hold solvent tubing in place at the bottom of the bottle. Most stainless steel inlet filter options work well for keeping tubing positioned for consistent solvent pickup.

IDEX General Use Inlet Stainless Steel Solvent Filters

Disposable inlet filters for routine LC solvent filtration and higher-flow applications

IDEX general use inlet stainless steel solvent filters provide reliable particulate protection at the solvent reservoir, helping prevent debris from entering LC and UHPLC flow paths. These inlet filters are a practical choice for routine solvent filtration, general laboratory use, and preparative workflows requiring higher flow capability.

  • ▸ Disposable design for easy replacement and reduced maintenance time
  • ▸ Suitable for general-use and prep solvent filtration where higher flow rates are needed
  • ▸ Stainless steel construction helps provide durable performance in compatible solvent systems

Filters should be changed periodically to maintain consistent solvent delivery and protect system components. For filters using a plastic fitting, tubing can be reconnected by finger-tightening the fitting into the new filter. Filter designs with stems allow easy insertion into inlet tubing for fast replacement.

IDEX Stainless Steel Bottom-of-the-Bottle™ Solvent Filters

Replaceable stainless steel filter cups designed to maximize solvent recovery

IDEX stainless steel Bottom-of-the-Bottle™ solvent filters are designed to draw solvent from the lowest practical point in the reservoir while maintaining inlet filtration. This helps reduce solvent waste, support consistent solvent pickup, and protect LC system hardware from particulate contamination.

  • ▸ Replaceable stainless steel filter cups simplify routine maintenance
  • ▸ Draw solvent from within 1/8" of the bottom of the solvent bottle
  • ▸ Helps keep inlet tubing positioned near the bottom of the reservoir for reliable solvent delivery

These filters are well suited for laboratories that want the chemical compatibility and durability of stainless steel with a solvent-saving bottom-of-the-bottle design. They are commonly used to protect pumps, valves, and columns while helping maintain steady mobile phase flow.

Stainless Steel Solvent Filters

PART NO DESCRIPTION TUBING POROSITY FLOW RATE* MATERIAL
INLET SOLVENT FILTERS FOR ANALYTICAL HPLC
A-242 Inlet-Solvent Filter with One-Piece Fitting 1/8" OD 2 µm 10 mL/min PCTFE, 316 SS
A-243 A-242, 5/pk 1/8" OD 2 µm 10 mL/min PCTFE, 316 SS
A-302 Inlet Solvent Filter with stem 1/16" ID 10 µm 40 mL/min 316 SS
A-302A Inlet Solvent Filter with Flangeless Fittings 1/8" OD 10 µm 40 mL/min PCTFE, SSE
A-309 Inlet Solvent Filter with stem 1/16" ID 10 µm 40 mL/min 316 SS
A-231A Inlet Solvent Filter with Flangeless Fittings 3/16" OD 20 µm 100 mL/min PCTFE, 316 SS
A-310 Inlet Solvent Filter with stem 1/8" ID 10 µm 40 mL/min 316 SS
INLET SOLVENT FILTERS FOR PREPARATIVE HPLC SYSTEMS
A-225 Inlet Solvent Filter with stem 1/16" ID 20 µm 100 mL/min 316 SS
A-225A Inlet solvent filter with Flangeless Fittings 1/8" OD 20 µm 100 mL/min PCTFE, 316 SS
A-227A Inlet Solvent Filter with Flangeless Fittings 1/4" OD 10 µm 100 mL/min PCTFE, 316 SS
A-230A Inlet Solvent Filter with Flangeless Fittings 1/4" OD 20 µm 100 mL/min PCTFE, 316 SS
A-311 Inlet Solvent Filter with stem 1/16" OD 10 µm 100 mL/min 316 SS
A-311A Inlet Solvent Filter with Flangeless Fittings 1/8" OD 10 µm 100 mL/min PCTFE, 316 SS
STAINLESS STEEL BOTTOM-OF-THE-BOTTLE SOLVENT FILTERS
A-550 B.O.B. Filter Assembly with A-520 filter cup 1/8" OD 10 µm 40 mL/min PEEK, ETFE, 316 SS
A-551 B.O.B. Filter Assembly with A-522 filter cup 1/8" OD 2 µm 10 mL/min PEEK, ETFE, 316 SS
A-520X Replacement Solvent Filter Cups, 10/pk — 10 µm 40 mL/min 316 SS
A-522X Replacement Solvent Filter Cups, 10/pk — 2 µm 10 mL/min 316 SS

IDEX All-PEEK Bottom-of-the-Bottle Solvent Filters

Biocompatible bottom-of-the-bottle filtration with no fittings required

IDEX All-PEEK Bottom-of-the-Bottle solvent filters are biocompatible filtering units made from 100% PEEK polymer. They are designed for easy operation, with no fittings required, making them a strong choice for applications where metal-free solvent contact and simple installation are important.

  • ▸ Most recommended filtering unit for biocompatible bottom-of-the-bottle solvent filtration
  • ▸ Easy operation with no fittings required
  • ▸ Primary 2 µm or 10 µm bottom frit draws solvent from within 0.080" (2.0 mm) of the bottle bottom
  • ▸ Secondary 2 µm side frit may be used for 1/8" OD helium sparging

To use the All-PEEK filter, press appropriately sized fluoropolymer tubing firmly into the top holes. The integrated PEEK frit design supports efficient solvent pickup while helping protect downstream LC system components from particulate contamination.

IDEX UHMWPE Bottom-of-the-Bottle Solvent Filters

Economical polymer inlet filters for low-residual-volume solvent pickup

IDEX UHMWPE Bottom-of-the-Bottle solvent filters are economical inlet filtration options designed to reduce unused solvent volume while protecting LC systems from particulate matter. The design allows tubing to pass through the bottom of the filter cup, enabling the filter to draw solvent very close to the bottom of the reservoir.

  • ▸ Replaceable filter cup design for routine laboratory use
  • ▸ Economical choice for compatible LC solvent filtration workflows
  • ▸ Constructed from UHMWPE and ETFE materials
  • ▸ Draws solvent from within 0.10" (2.5 mm) of the bottom of the solvent bottle

UHMWPE is a hydrophobic material. To establish proper surface wetting, the filter may need to be primed with methanol or acetonitrile before use.

These filters are a practical option when solvent recovery, simple replacement, and cost-effective polymer construction are key selection factors.

All-PEEK & UHMWPE BOB Solvent Filters

PART NO DESCRIPTION TUBING OD POROSITY
UHMWPE BOTTOM-OF-THE-BOTTLE SOLVENT FILTERS
A-445 UHMWPE Filter Assembly 1/16" 10 µm
A-446 UHMWPE Filter Assembly 1/8" 10 µm
A-427 Replacement Solvent Filter Cups, 5/pk — 10 µm
ALL-PEEK BOTTOM-OF-THE-BOTTLE SOLVENT FILTERS
A-437 PEEK Filter, for small-neck (GL-38) bottles 1/8" 2 µm
A-438 PEEK Filter, for small-neck (GL-38) bottles 1/8" 10 µm

Agilent Glass Inlet Solvent Filters

Glass inlet solvent filtration for Agilent LC solvent reservoir setups

Agilent glass inlet solvent filters provide particulate protection at the solvent reservoir while offering glass material compatibility for supported LC solvent delivery setups. These filters are designed for use with 1/8" OD tubing and help reduce the risk of particulates entering pumps, valves, and columns.

Agilent Glass Inlet Solvent Filters

PART NO DESCRIPTION TUBING POROSITY FLOW RATE* MATERIAL
AGILENT GLASS INLET SOLVENT FILTERS
5041-2168 Glass Inlet Solvent Filter 1/8" OD 20 µm 10 mL/min Glass
Key Definitions ▶
Inlet Solvent Filter
A filtration device placed at the solvent reservoir inlet to remove particulate contamination before it enters pumps, valves, and chromatographic flow paths.
Bottom-of-the-Bottle Filter
A specialized inlet filter designed to draw solvent from the lowest possible point in a bottle, helping maximize solvent usage while maintaining continuous filtration.
PEEK Filter Assembly
A biocompatible inlet filter constructed from PEEK polymer, offering excellent chemical resistance and integrated frits for analytical and bioanalytical applications.
UHMWPE Filter
An economical polymer inlet filter made from ultra-high-molecular-weight polyethylene that allows tubing to pass through the filter cup for near-bottom solvent pickup.
Helium Sparging Port
A secondary frit or inlet on certain PEEK bottom-of-the-bottle filters that supports 1/8" OD helium lines for solvent degassing and bubble suppression.
Frequently Asked Questions ▶
Why should I use an inlet solvent filter?
Inlet solvent filters remove particulate contamination before it enters your LC system, helping protect pumps, valves, and columns while improving overall system reliability.
What is the advantage of bottom-of-the-bottle filters?
Bottom-of-the-bottle filters draw solvent from the lowest possible point in the reservoir, helping reduce solvent waste while maintaining continuous filtration.
Which material should I choose: stainless steel, PEEK, or UHMWPE?
Stainless steel filters are ideal for higher-flow applications. PEEK filters offer biocompatibility and excellent chemical resistance. UHMWPE filters provide an economical option for routine laboratory use with near-bottom solvent pickup.
How often should inlet solvent filters be replaced?
Filters should be replaced periodically based on solvent cleanliness and system usage. Increasing backpressure or reduced flow are common indicators that replacement is needed.
Can I use helium sparging with bottom-of-the-bottle filters?
Yes. All-PEEK bottom-of-the-bottle filters include a secondary 2 µm frit that supports optional 1/8" OD helium sparging for efficient solvent degassing.