I did an undergraduate experiment and could use some help in interpreting the $\ce{^1H}$ NMR spectra.
This was the task: About $\pu{5-10mg}$ (1-2 drops) distilled amine is weighed in a NMR tube. Put the top on the tube immediately to prevent reaction between the amine and $\ce{CO2}$ from the air. Weigh exactly 1.1 equivalent of (S)-alpha-acetoxyphenylacetic acid. Dissolve the acid in about $\pu{0.4 ml }\ce{CDCl3}$ and transfer the solution to the NMR tube.
This here is the $\ce{^1H}$ NMR:
Could I get affirmation of the choices drawn in red and what does the shift at $\pu{4.2ppm}$ correspond to? Could it be because $\ce{CO2}$ reacted with the amine?
(ChemdDraw was used to get the molecular figure and chemical shifts on the figure.)