What are Extractables and Where Do They Come From?

A syringe filter extractable is an undesired artifact contributed to the sample fluid from the filter device. This material may be a membrane or housing formulation component, or a component introduced during the manufacturing or packaging process. There are several mechanisms (solubility, particle displacement, chemical interaction, and diffusion) whereby extractable materials may leach into the sample during sample preparation. Of these mechanisms, solubility and particle displacement are more prevalent.

The appearance of extractable materials from a syringe tip device depends on the solubility of device components in the sample fluid. The polymeric resins, solvents, pore formers and other chemical components such as housing materials utilized during device manufacturing may potentially extract. Solubility relates to chemical compatibility. As membrane and/or housing components become more soluble with sample fluid components, extractable materials will increase. To determine whether a syringe filter is compatible with the sample fluid, all sample constituents(both major and minor components) require consideration. Because solubility is dependent on temperature, concentration, and exposure time, all of these parameters are significant in determining chemical compatibility.

Displacement can occur when residual manufacturing materials, once caught in the pore structure of the membrane, are dislodged.