Do Filter Membranes Release Leachable Compounds into the Mobile Phase Following Vacuum Filtration?

Vacuum filtration of eluents is a common practice to protect chromatographic columns from particles. Leachables, from components that a solvent comes in contact with, can cause interference during chromatographic analysis. Sartorius membrane filter discs were therefore tested to determine if leachable compounds are detected in the eluents following filtration of the solvents through these filters.

The solvents - pure water, a phosphate buffer, and pure acetonitrile were used to simulate typical eluents to be filtered. The most frequently used membrane types, regenerated cellulose (RC) and polyamide (PA), with a pore size of 0.2 μm were tested as filter materials. While the RC filter showed no difference to the reference, we found small peaks for the PA filter using HPLC-UV/VIS and HRMS. The observation was supported by the measurement of the total organic carbon (TOC) of the water extracts.

Overall, the amount of leachables is very low. Therefore, it can be concluded that for most applications the filter discs made of both RC and PA are well-suited for the filtration of eluents.