Agilent, 821075-920, Poroshell StableBond 300 C18, 2.1 x 12.5 mm, 5 µm, guard cartridge (ZGC) 4/pk

Agilent Poroshell 300SB-C18 guard cartridges protect a compatible reversed-phase analytical LC column from strongly retained matrix components and particulate-related fouling. Each cartridge contains superficially porous 5 µm C18 particles with approximately 300 Å pores, providing a short protective bed for biomolecule separations. The guard format measures 2.1 × 12.5 mm, and four replacement cartridges are supplied per pack. StableBond chemistry supports low-pH reversed-phase operation, including methods for intact proteins and other large analytes when paired with a suitable analytical column. Install a cartridge in the designated guard hardware, confirm correct flow direction and equilibrate with the intended mobile phase. Monitor backpressure and peak shape to determine when to replace the guard rather than forcing contaminated material onto the analytical column. The guard cartridge is not a complete analytical column, and the holder must be ordered or provided separately.