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- Posts: 1
- Joined: Sat Sep 15, 2018 5:01 pm
I am analyzing petroleum samples using a GCxGC-TofMS instrument. I am specifically focusing on the n-alkanes and aromatic hydrocarbons. In a recent analysis I noticed the two hydrocarbon classes elution order switched in the 2nd dimension ie. aromatic peaks seen below hydrocarbon peaks. I am using a normal phase setup ( non polar column in 1st dimension, midpolar column in 2nd dimension) so this was unexpected. I then injected an n-alkane C8-C20 standard just to check and the peaks eluted after 2 sec in the 2nd dimension.
Might this be an instrumentation problem or perhaps the GC conditions? Any advice would be highly appreciated