I am running a thermal desorption GC/MS of a silicone sample. The chromatogram is clean and nice, however, one of the siloxane groups is showing as 5 peaks (well separated) at times 7.1, 8.2, 8.7, 9.8, and 10.5. What is the explanation for this?
What said above is right. Siloxane peak may come from packing stuff of absorption tubes as well when the tubes were over reconditioned or used for long.
Another possibility is from cold trap (absorbent, glass wool, etc.).
Really common, especially if this is the first run of the day. They come out of your septum and concentrate in your injector port or on the head of the column. Always make sure you run a blank as your first injection!
This can also come from phase degradation in your column, especially if you are injecting high water or acidic compounds.
Given that you are thermally injecting silicone you are almost certain to see siloxanes in your chromatogram, especially if you do not purge the air out of your thermal desorption tube before you begin to heat it.
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