Remove the phenolic fraction of humic acids, tannic acids, lignins, anthocyanins, and azodyes from sample matrices. Thermo Scientific™ Dionex™ OnGuard™ II P Cartridges are an off-line sample preparation technique that uses polyvinylpyrrolidone (PVP) polymer with very high selectivity to eliminate these matrix interferences to improve IC performance and facilitate low-level ion analysis. Use Dionex OnGuard II P Cartridges singly or in series, or pretreat up to 12 samples in parallel using the optional Thermo Scientific Dionex OnGuard Sample Prep Station.