Print

Print


Dear All,

This is more of a GC/MS question but I was hoping someone might have 
some insight into my problem. After a period of low use on the GC/MS, we 
recently replaced the MS filament and cleaned the MS. We are observing a 
series of siloxane peaks in the hexane blanks (see attached). 
Interestingly, there is no observable siloxane contamination when BSTFA 
blanks are run. We have used 2 different lots of GC grade hexane, one of 
which I have previously used and had no contamination. Both lots produce 
virtually identical chromatograms. I have replaced the septum, inlet 
liner, syringe, and replaced the column. The problem is replicated with 
the new column (which was previously fine). Columns are Restek RXI-5MS 
and RXI-5 Sil MS.

Any thoughts as to what might be causing this would be much appreciated.

Marshall