What would be the best initial solvent system to try with for validation studies of terpenes and volatile terpenoids using RP hplc rather than using GCMS?
Many terpenes are purified with water/methanol or water/acetonitrile using a high concentration of organic. These generally possess one or more hydroxyl groups. Less polar terpenes may be run with non-aqueous reverse phase (ethanol replaces water, elute with hexane- these two solvents shouldn't interfere with detection, use these solvents on silica-based C18, not polymeric reverse phase).
Also consider water/THF as a solvent system, mostly containing THF. This is less polar than methanol or acetonitrile.