Glass fiber (GF) syringe filters are ideal for the filtration of extremely viscous samples which could clog other standard syringe filters. These hydrophobic syringe filters are known for their excellent compatibility with organic solvents, strong acids, and bases. Glass fiber (GF) syringe filters are ideal for the filtration of extremely viscous samples which could clog other standard syringe filters. These hydrophobic syringe filters are known for their excellent compatibility with organic solvents, strong acids, and bases.