Woah! You have to be more specific. GC requires that the molecule be detectable and volatile, while HPLC that the molecule be detectable and soluble. Thus, it is the molecule that decides the analytical method. Therefore, you who will have to decide what metabolites you what to analyze.
The easiest method is to perform a liquid-liquid extraction with Hexane, ultrafilter, and inject into a GC. However, you will only quantitate a 'small' number of your metabolites.
thank you sir, I want to analyze amino acids and TCA cycle intermediates with GC MS. iI think liquid-liquid extraction is a good way, but about the volumn, temperature and solvent, I am not sure about that.