Phenex-GF (Glass Fiber) filters are made of inert borosilicate glass and have a nominal 1.2 μm pore size. They are commonly used with highly viscous samples or samples that contain high concentrations of particulate matter (e.g., food analysis, biological samples soil samples, fermentation broth samples, removal of yeasts, molds, etc.).

Glass Fiber filters can be used alone or in series with other Phenex filter membranes such as the 0.45 μm pore Phenex-RC filter syringe filers to reduce clogging of the membrane and optimize flow.