Chromatography Forum

On reverse engineering. I have looked for additives in motor oil using GCxGC-TOFMS. For that you need GCxGC-MS and some experience picking things out with a mass spec. And, that is the starting point. Picking copper or zinc out of the mix using mass spec is not easy; there is no disstinctive pattern that easily allows you to identify these compunds - at least not one that I was able to find. With one GC dimension - get a column that can take high temperatures, a DB-1 or DB-5 type. For petrolium compunds I liked a 50 M x 0.32 id x 0.32 u DB-1 column run under conditions similar to ASTM D5134, but running the column up to higher temperatures to get the higher boilers in heavier mixtures. With GCxGC, I used a BPx-50 column for the second dimension of separation.

If you are going to be using hydrogen I'd get a very narrow column say .18 and if you need high temp they make high temperature db-1 and db-5's that can go up to 400 deg C or more.