I think you should go for GC or GC-MS analysis for citrenellol, carvacrol etc rather than HPLC.

The first thing is your kind of material, is it essential oils or extract? Then the complexity of the matrix of your analytes. The GC or GC-MS have much more theoretical plates for separating the compounds rather than HPLC. In this way most of the analysis of the light terpene are carried out in GC. By the way if you can separate your analyte from its matrix in HPLC you can quantify it without any problem.

It is possible, you can use a C-18 with a high organic content mobile phase. I was working with cantaxanthin starting with acetonitrile/water: 9/1 and increasing to 100% acetonitrile. Also there are columns like C-30 for carotenoids that can work with apolar compounds.

Thanks a lot to all for answers..

Mr. Caraccioli, could you please explain the wavelength for terpene analysis?

you have to work in the UV region (200-300 nm), wavelength depends on the compounds in your sample. Carvacrol has a max at 273 nm See: Pharmacogn Mag. 2010 Jul-Sep; 6(23): 154–158. doi: 10.4103/0973-1296.66927

Best regards

Thanks Sebastian..All best wishes..

yes, we can use the type of HPLC reverse phase , the hypersil C18 (apolar) and the mobile phase (polar): acetonitril + water