I can't find a compound that should be in a standard mix

I'm working with a  5977B MSD with an 8890 GC.  I've been trying to identify all of the compounds in the Sigma Terpene Mix B (https://www.sigmaaldrich.com/US/en/product/supelco/crm40937).  I'm able to identify all of them fine except for phytol.  I just can't seem to find it.  I'm also pretty sure that it's a mix of isomers, so there should be multiple peaks.

For a while I thought that I had found them, there are two significant peaks, one is coming up as palmitic acid and another as stearic acid.  They're both long hydrocarbon chains like phytol, but when I do a serial dilution of the mix they remain at more-or-less constant concentrations, so I think they are present as a result of some processing I'm doing.  They also come up later in the run (which from other reading I have done appears to be when phytol should come out.

I've searched in NIST for what the spectra should look like and have tried extracting ions in their chromatographs, but that doesn't seem to help (although it does pull up the palmitic acid and stearic acid).  There are other compounds that are highlighted, but they don't appear to be good matches either.

I didn't know if anyone had any suggestions for additional ways I could try to find this stubborn compound.  Thanks.

Parents
  • Hello, 

    Phytol should be straight forward to detect in this mixture. It elutes after the sesquiterpenes. What is your injection temperature? Make sure its high enough to vaporize the phytol. 230C or higher would be high enough. Same goes for the oven program. Make sure it goes high enough to elute the phytol. Going up to 250 C should be enough.

    What kind of column are you using?

    If you are seeing palmitic acid and stearic acid constantly your liner or column might be contaminated. Might want to clean that up. 

Reply
  • Hello, 

    Phytol should be straight forward to detect in this mixture. It elutes after the sesquiterpenes. What is your injection temperature? Make sure its high enough to vaporize the phytol. 230C or higher would be high enough. Same goes for the oven program. Make sure it goes high enough to elute the phytol. Going up to 250 C should be enough.

    What kind of column are you using?

    If you are seeing palmitic acid and stearic acid constantly your liner or column might be contaminated. Might want to clean that up. 

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