April 12, 2012
Spectral data that exhibit weak signals (low S/N) can easily be misinterpreted. A good approach is to check the data against other data to confirm whether the signal is real or an artefact.
For an unknown compound, the 1H -13C HSQC spectrum below is shown at two different intensity thresholds. The aromatic protons at 6.97 and 7.00 ppm equate to 4 non-exchangeable hydrogen atoms. Is the correlation between the 1H signal at 6.97 ppm and the carbon at 122 ppm real or an artefact?