NIST Library

Discussions about GC-MS, LC-MS, LC-FTIR, and other "coupled" analytical techniques.

6 posts Page 1 of 1
Hi all,
Does anyone know why the structure of identified compound is not shown on "spec list" in NIST library? I have "?" instead of the structure (please see the picture below)


Image
As someone who actually "built" two Agilent search libraries for my company by injecting standards, my guess is that the pattern for methyl palmitate did not have a structure entered in for that entry.

I see your software matched your peak with methyl palmitate, so not sure I understand the question.

In the early days of GCMS search libraries (1990s), it was not uncommon for purchased NIST libraries to have such omissions.
Yes, the software matched my peak with methyl palmitate, but my question is why the chemica structure of methyl palmitate is not shown in "spect list" (spect list is the upper pane in the left side) and as could be seen, no structure is shown. Instead, "?" is appeared.

Is there any setting for viewing structure in spect list?
Two statements taken from the NIST Library web page could explain it.

"When a spectrum is associated with a structure in the Spectrum Information dialog box of the Librarian tab view, the InChI Key is automatically associated with the spectrum."

"Spectra in the NIST Mass Spectral Library may have information including formula, mass (nominal, exact, or both) names and synonyms, structures, and more"

This implies that not all entries will have all the information, so there may not be a structure reference included for that analyte. It seems to be showing the structure for the Hexadecanoic Acid Methyl Ester in the entry at the bottom of your snapshot so I would guess Methyl Palmitate does not have a structure included in the database.
The past is there to guide us into the future, not to dwell in.
Thanks James

I've figured out that structure of compound in "spect list" has different database than the "Hit list"?
But, I expect when I inject pure standard with a match factor as high as 995 (and 98% probability), the structure is shown in "spect list". Did I get it right?
M.John wrote:
Thanks James

I've figured out that structure of compound in "spect list" has different database than the "Hit list"?
But, I expect when I inject pure standard with a match factor as high as 995 (and 98% probability), the structure is shown in "spect list". Did I get it right?


I can't answer that question as I have only used the NIST library with the Agilent software.
The past is there to guide us into the future, not to dwell in.
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