To confirm the BOC is removed, a TLC will be the easiest.
The NMR will also show the removal of the t-butyl peak ~1.5ppm. The NH3+ is difficult to see and not reliable. You could run 19F NMR to see the TFA salt
I have done BOC-deprotection by TFA, and reaction was monitored by TLC, even by NMR but ATR does not showing any -NH2 peak. Eventually I pass ammonia gas to remove TFA-salt but unfortunate ATR is not showing any primary amine (-NH2) peak yet.