My student sent a labeled compound for CHN analysis.  Her data came back all wrong.  I remembered (in the dim recesses...) that when doing CHN analyses for deuterated compounds, you have to do something different.  But I have no idea what it is.  But, technology has advanced in the intervening years, so I had chemdraw automatically calculate numbers.

Chemdraw calcd for C₁₄H₁₅D₆NO₂:  %C:  69.67, %H:  11.27, %N:  5.80

Chemdraw calcd for C₁₄H₂₁NO₂:  %C:  71.46, %H:  8.99, %N:  5.95