Chromatography Forum

JI2002, I will do that, thanks again.

The results are in. I now have a very simple spectrum - m/z 228 at 100%, basically no other m/z in the spectrum. That leads to the question what this could be... http://www.flavornet.org/mw.html shows only three substances with 228. (CAS:30673-36-0 butyl decanoate; CAS:106-33-2 ethyl laurate, ethyl dodecanoate; CAS:1117-55-1 hexyl octanoate)
None of this has an appropriate spectrum.

First question is where did the sample come from? Some information about the origin could help answer the question. If you have purchased this - call the vendor and tell them what you have found.

M+1 and M+2 can give you a hint about composition - but I work with quads, sectors and TOFs. I gather that traps can be a bit tricky about ratios for low abundance ions...

I did a search for CASrn 39647-11-5 in the 4th Ed of the Adams library and the Wiley FFSC 1.3 libraries. The spectra are very similar.

This compound is a methyl ester and a cyclic ketone with a nominal mass of 226. The peak at m/z 156 is an odd-electron ion. These types of compounds are difficult at best when using a internal ionization QIT GC-MS. The peak at m/z 227 in you mass spectrum represents a protonated molecule formed by the ion/molecule reactions of ions with m/z 156 and the unionized molecules.

Dilute the sample. Even at very low concentrations you will still see an abnormally high intensity for m/z 227 given the low intensity of the peak at m/z 226 in the spectrum acquired using a transmission quadrupole instrument. The spectrum in the 2nd Ed. Of the Adams library is some what different than that shown in the 4th Ed. And has a peak at m/z 227 which is about twice the intensity of the peak at m/z 226. Both peaks in this mass spectrum are < 5%.

David, thanks for your thoughts. I didn't know there is a Mass Spectral database from Adams? Do you refer to Robert P. Adams, who wrote "Identification of Essential Oil Components By Gas Chromatography/Mass Spectrometry"? Would you mind giving a link?

I'll do as you suggested. Thanks again!

Don, the supplier "swears an oath" the sample came directly from a Firmenich package. They are not very talkative, especially not about their captives

Yes, I am talking about Robert P Adams and this is the 4th Ed. of his book/database from Allured Publishing

http://www.alluredbooks.com/Flavor-Chem ... n-p52.html

The book has structures; the electronic database does not. Each name in the electronic version of the database begins with the retention time making a name search in the NIST MS Search Program tricky. You have uses the setting that ignores numbers in the name.

We built our own GCMS fragrance library, injecting 20 pure compounds each night, then entering the spectra into our own GCMS library the next day. It was a several-month project, including retention indexes v. ethyl fatty acid esters, because that's what perfumers use. That was in early 1990s, on HP 5890/5971. Works good, and since it's ours, we can put on all our GCMS computers.

Yeah, I built my own LC-ToF ESI library with fragmentation using insource CID. Up to 1,200 compounds now.