What should you know when selecting a syringe filter?

**Author:Orgianl from Internet

Syringe filters offer excellent performance: they reduce system downtime, extend the lifespan of chromatographic columns, and enhance sample integrity. They feature high mechanical strength, exhibit resistance to most organic solvents, and are particularly well-suited for use with alkaline solutions.

Does your application require resistance to acids, bases, or organic solvents? When choosing a syringe filter for sample preparation or mobile phase filtration, chemical compatibility is a critical factor. The following general selection principles serve only as a basic reference; please consult a "Syringe Filter Chemical Compatibility Chart" to determine the appropriate filter type for your specific application.

For filtering aqueous samples, hydrophilic membranes—which have an affinity for water—are the preferred choice. Options include filters equipped with GHP (hydrophilic polypropylene), PES (polyethersulfone), nylon, or PVDF (polyvinylidene fluoride) membranes.

Hydrophobic membranes repel water and are inert toward aggressive organic solvents, making them the ideal choice for handling gases and organic solvents. In such cases, filters equipped with PTFE (hydrophobic polytetrafluoroethylene) membranes should be used.

Different polymeric membranes possess varying degrees of chemical compatibility. Depending on the application and chemical compatibility requirements, one or more types of membrane-filter combinations may be suitable. Generally, due to limitations related to hydrophobicity/hydrophilicity and chemical compatibility, no single type of filter can accommodate every possible application.

Filters are used to remove unwanted particulates and improve sample purity. However, selecting an inappropriate filter can turn it into a source of contamination, as extractables may leach from the filter assembly into the sample. Such artifacts can compromise the accuracy of analytical results; issues caused by extractables include co-elution, quantification errors, and the appearance of extraneous peaks.

Filters with low adsorption characteristics should be selected—for example, syringe filters equipped with GHP membranes. GHP membranes exhibit exceptionally low binding affinity for biomolecules, with typical binding levels well below 1%.