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Re-evaluating the data from MS and NMR … Part 2

October 20, 2009
by Arvin Moser, Team Manager, Application Scientists, ACD/Labs

Whenever data appear to contradict each other, an instinctive reaction to this problem is to collect more data. Collecting more data can help to understand the problem and/or complicate the matter. Remember the model for Elucidation Evolution? Maximize data extraction (MDE) while minimizing data collection (MDC).

Recap of the problem: The ESI+ MS shows a single [M+H]+ at m/z 102 allowing a maximum carbon count of 8. The 13C NMR shows there to be 12 carbons. How can the data from the MS and NMR present such different results for the same unknown?

The 1H NMR spectrum below is complicated due to significant peak overlap. As such, it does not offer any further insight into the problem.


Is there any data (or a different interpretation) that can assist in deciphering what the unknown is and thus explain why the MS and NMR data appear to contradict each other?


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