The HD-C18 phase is best suited to separate highly hydrophobic, small molecules with small structural differences - for example isomers. The density of the C18 chains on the surface of the organosilica hybrid particles is higher compared to the Scepter HD-C18. As a result, molecules that can get between the C18 chains due to their size experience more interactions than molecules whose molecular structure does not allow them to get in between, or only partially. Thus, molecules with small structural differences can be separated better.