[AWK]

NMR will allow you to find the ratio of N-ethyl to O-ethyl derivatives in the crude reaction product, and GC-MS to identify these three peaks (the O-ethyl derivative partially isomerizes at temperatures above 200C).

[Babcock_Hall]

Now that you have alternative hypotheses, what should you do next, assuming that you had access to all that you needed?

NMR/GC MS?
I suspect that either one would work.