Ed9362. Why don't you whack a whopping great handful of pure sodium chloride into a small sample of your grog when you get out of your car at the lab to 'denature' it and then take it in for the gas chromatograph? Just disregard any Na and Cl hits. Shouldn't affect any of the alcohol components too much short term.
to be honest im not sure how the lab people would react if I asked them to run alcohol through one of their machines. I do have access to an ADA which I could run through I guess, it would give an idea about what is in the product but not ratios.
I might give it a go in a few months, we have union problems at the moment and the company will use any excuse they can to fire us