Product List

Non-Aqueous Syringe Filters

*If you require a pore size or diameter not listed in the table please contact us to see if we can provide you with a syringe filter to meet your specifications.

Aqueous Syringe Filters

*If you require a pore size or diameter not listed in the table please contact us to see if we can provide you with a syringe filter to meet your specifications.

Specifications

Membrane Filtration Overview

Membrane filtration is a method of removing particulates from solution without the need for any heating. This filtration method is typically used in other processes, such as sublimation and distillation. It works simply by restricting the movement of particles above a specific size through a porous material. Typically membrane filtration is separated into several categories dependent upon particle size. These categories are: particle filtration, microfiltration, ultrafiltration, nanofiltraion, and reverse osmosis. These different categories cover particle sizes, ranging from centimetres down to angstroms. Below is an image highlighting the range covered by microfiltration membranes highlighting the types of materials that can be filtered out.

Membrane filtration is used in a variety of scientific fields including biotechnology, pharmaceuticals, medicine, chemistry, and semiconductor manufacturing. Each field has very different requirements for the filters and the choice of filter type can depend upon the solvent being filtered, the size of particles that need removing, whether the filters need to be sterile, the volume of solution being filtered, and the temperature of your solution. If you are unsure about what particular membrane would best suit your needs please see the following section.

Choosing the Correct Syringe Filter

At Ossila, we offer five different membrane materials for our syringe filters:

• Hydrophobic PTFE (Polytetrafluoroethylene)
• Hydrophilic PTFE
• Hydrophobic PVDF (Polyvinylidene fluoride)
• PES (Polyethersulfone)
• Nylon

PTFE can be used with almost any solvent due to its low reactivity and low extractables. Additionally, PTFE has extremely high thermal stability, allowing for a wider range of processing temperatures compared to standard membrane materials. However, PTFE is naturally hydrophobic, which can make the filtering of aqueous solutions difficult. To counter this, we offer the option of hydrophilic PTFE - in which the membrane surface has been treated to improve the wetting on aqueous solutions.

PVDF like PTFE is naturally hydrophobic and like PTFE offers high chemical resistance against a wide range of different chemicals. PVDF also has the advantage of low protein binding in comparison to materials such as PTFE.

Due to its naturally hydrophilic nature, PES is compatible with aqueous solutions and alcohols. In fact, PES is highly recommended for the use of for filtering aqueous solutions. This is due to the reduced presence of extractables from not having to treat the membranes surface with wetting agents. In addition, due to its extremely low protein binding, PES offers superior performance for use with biological samples and culture media.

Like PES, nylon is naturally hydrophilic - making it suitable for use for filtering aqueous solutions, and like PES it results in a low level of extractables within the filtered solution. Nylon has a higher chemical resistance than PES making it suitable for a wider range of organic solvents including ketones, esters, DMF and DMSO.

Below is a table showing the sizes of solutions suitable for different filter diameters:

We have found that 13 mm diameter filters provide the best combination of filtering capability/capacity, with minimal solution loss.

The pore size of your chosen filter depends on the material you wish to remove. As the membrane material has a pore size distribution of around an average size, it is possible that particles bigger than the stated pore size may pass through. We recommend choosing a pore size just below the minimum size of particle you wish to remove.

To the best of our knowledge the technical information provided here is accurate. However, Ossila assume no liability for the accuracy of this information. The values provided here are typical at the time of manufacture and may vary over time and from batch to batch.