Alternative Selectivity to C18 Columns. Shim-pack GIST Phenyl-Hexyl columns are bonded with a phenyl ring together with a hexyl (C6) chain, which provides complementary selectivity to straight alkyl-chain columns due to its ?-? interactions and hydrophobic interactions. Furthermore, Shim-pack GIST Phenyl-Hexyl maintains the same ultra-high inertness, wide pH range and high durability as the Shim-pack GIST C18, achieving stronger retention than other phenyl columns as well as reducing or eliminating adsorption of polar compounds. Bonded Phase Phenylhexyl Groups, Particle Size 3 ?m, 5 ?m, Pore Size 10 nm, Surface Area 350 m2/g, Carbon Loading 9 %, End-capping Yes, pH Range 1 to 10, USP Code L11.