May 23, 2008
Typically, structure elucidation via NMR can be ascribed by a stepwise workflow:
1. a sample is prepared for NMR, 2. the NMR instrument is optimized for data collection, 3. NMR data is acquired, 4. the spectral data is processed, 5. the spectral data is searched/compared to an internal database for possible hits or similarities, 6. the NMR data is pieced together to create a list of candidate structures, 7. the candidate structures are checked/verified against additional data.
Structure elucidation is not as simple as it sounds. Collecting NMR data on an unknown sample and heading straight down the path to solve it is not a guarantee for success. Optimizing data collection is a critical step and one that is frequently overlooked. Here is a list of issues that may arise when step 2 is inadequately applied: peaks are poorly shimmed, a probe is poorly tuned and/or matched, the presence of solvent impurities, outside interferences on the instrument, the wrong experiment parameters are setup , and the list goes on. The major consequence of any of these actions is NMR information can be misinterpreted.
TIP: spending a few minutes to quickly check the processed NMR data before moving onto the next step can save you loads of time and anguish.