Chromatography Forum

Hi ! guys
Let me know exactly when a compound should be developed for gc?

When it can't be analyzed by HPLC.
When a GC is the only instrument available.

Addy, please explain your question with more detail so the other members of the forum can give you a more intelligent answer. There is no way to correctly answer your question the way it is stated.

Thanks for reply skunked_once.

Comment appreciated, I just wanted to ask how can we decide for an unknown compound by its initial data (i.e. Mass,NMR,IR,Solubility etc.) that
it can be analysed on GC or HPLC or on both.

First of all, the component needs to be volatile in order to be determined by GC. The stability of the component is also important, if it's unstable at high temperature then it's not appropriate (usually the detector is set at about 150-250 degrees).

Addy,

Now the answer gets more complex. For GC, the sample must be volatile and temperature stable as vliu explained. In addition, there are different types of GC detectors which may be used depending on the type of molecule and which elements or functional groups it contains. For HPLC, the sample must be soluble in either an aqueous mobile phase or a non-polar mobile phase. Type of detector is also an issue so chemical structure comes into play here also. Access to a mass spectrometry detector coupled to either GC or HPLC is the most useful because of the compound identification aspects. For other types of GC and HPLC detectors, relative sensitivities of each are an issue to consider. Descriptions of the details of each is beyond the scope of this response. In the real world, the choice of GC or HPLC and type of detector often depends on what is available in the lab.