Membrane Disc Filter

What is the Membrane Disc Filter?

A membrane disc filter is a flat circular membrane placed in a holder for vacuum or pressure filtration. It is used for larger volumes, clarification and sterilisation by filtration, and it fits reusable holders.

Overview

The disc is a circular membrane, commonly 25–293 mm in diameter, made from PTFE, PVDF, PES, nylon, cellulose nitrate, cellulose acetate or glass fibre, with pore sizes from 0.1 to 5 µm. It is clamped in a filter holder, a vacuum flask assembly or a pressure vessel, and the liquid is drawn or pushed through. Discs are chosen for their chemical compatibility, flow rate and capacity, and glass fibre prefilter discs are often stacked above the membrane for dirty samples to extend life. They are used for clarifying large volumes, for sterilising heat-sensitive solutions, for air venting of vessels and for sample preparation where the holder must be reusable. Because the membrane is separate from the holder, the same holder works with different membranes and pore sizes.

How does it work?

A laboratory filter separates particles from liquid by passing the liquid through a porous membrane with a defined pore size. Particles larger than the pore are retained on the surface or within the structure, while the filtrate passes through. Membrane material determines chemical compatibility and adsorption: PTFE is inert to most solvents and is used for organic mobile phases, PVDF suits aqueous and mixed phases, nylon binds proteins and is used where adsorption is not an issue, and cellulose acetate and PES are used for aqueous and biological solutions. Pore size of 0.45 µm removes most particulates, while 0.22 µm is used for sterilisation by filtration because it retains bacteria. The housing, whether polypropylene syringe filter, a bottle-top unit or a centrifugal device, provides the driving force and the connection. Extractables and hold-up volume are the main performance risks.

What are the key features?

• Diameters 25–293 mm
• Pore sizes 0.1–5 µm
• Many membrane materials
• Used in reusable holders
• Glass fibre prefilter stacking
• Vacuum or pressure operation

What are the technical specifications?

A typical membrane disc filter configuration offers diameter of 25–293 mm, pore size of 0.1–5 µm, membrane of PTFE, PVDF, PES, nylon, CA, glass fibre, holder of Reusable, clamp or flask, operating mode of Vacuum or pressure and prefilter of Glass fibre option. Values are indicative of the product class; the exact figures for each configuration are confirmed on the quotation and the calibration documents supplied with the instrument.

Which applications is it used for?

The Membrane Disc Filter is used in large-volume clarification, sterilisation by filtration, vessel air venting and sample preparation with holders. Across the wider Filters class, laboratories also deploy it for sample clean-up before HPLC, mobile phase filtration and sterilisation by filtration.

Which standards and certifications apply?

Relevant standards and methods include USP <788> (particulate matter in injections), USP <665> (plastic components and systems), ISO 13485 (medical device quality management), ISO 10993 (biological evaluation of medical devices), EN ISO 11607 (packaging for terminally sterilized devices) and USP <1664> (assessment of drug product leachables). Certification candidates for this model are CE and ISO 9001 manufacturing; each is to be confirmed for the specific configuration before shipment, and certificates are supplied only where they have been issued.

Pre-rinse the filter with the solvent or mobile phase when the method is sensitive, because membranes contain extractables such as wetting agents or oligomers that can appear as peaks, especially with LC-MS. Use a filter with a larger pore or a glass fibre prefilter for dirty samples, since a clogged 0.22 µm filter is a common cause of lost samples. Do not use the same filter for different samples if carry-over matters, and never filter a sterile solution into a non-sterile container. Check the pressure rating of syringe filters, because high pressure can burst the housing and release particles. Store filters in their packaging and respect expiry, especially for sterile units. Record lot numbers, since extractables and adsorption can vary between lots.

How do I select the right Membrane Disc Filter?

Choose disc membranes when you have a reusable holder or need a specific material and diameter, and stack a prefilter for dirty samples. RFQ: diameter, pore size, membrane, holder and volume. Provide the diameter, membrane and volume.

How does it compare with other Filters variants?

Choose the membrane by the solvent, the analyte and the purpose. Use PTFE for organic solvents and aggressive chemicals, PVDF or PES for aqueous and mixed phases, and cellulose acetate for aqueous solutions where low protein binding is wanted. Choose 0.22 µm for sterilisation or where microbes must be removed, and 0.45 µm for general particulate removal before chromatography. Match the format to the volume: syringe filters for 1–100 mL, bottle-top units for 100 mL to several litres, disc filters for vacuum or pressure holders, and centrifugal units for small volumes and concentration. Confirm the housing is compatible with the solvent, check hold-up volume for small samples, and ask for extractables data when the method is sensitive. Do not use a filter that adsorbs the analyte, and verify recovery with your compounds.