I have a project that I want to do; really it is an experiment that would prove useful to another project of mine. I want to build a gas chromatograph. The specs. Capillary column Helium carrier Thermal Conductivity Detector The analyte is a mixture of CH4,N2 (for now) I already have the TCD made and it is functioning well, I just need some info on the capillary. Question: what will work well enough for a capillary column? Can I use a copper capillary as used for refrigeration? I know that the norm is a capillary that has a coating on the inside with a Stationary phase but will the walls of a copper or glass capillary suffice in this function? I suspect it all has do with the degree of separation that is needed but I am looking for some guidelines in this respect, just some empirical guidelines to help me get started. Probably for one to make a recommendation I might give some more information I just need to make an approximation as to the quantity of the components in the anilyte, rarely would I even need to separate a complicated mixture just the simple one that I exemplified. I guess that I could just buy some capillary and experiment but I just wanted your opinion on the matter. Thanks, Cheers!