Well, I think your teacher is saying to do 2,4-D in the GC, but, I do (and many other people) do 2,4-D via LC-MS all the time. Its quite easy and works very well.
Your teacher is clearly looking for a specific answer, and since I do not know your teacher and what you covered it is kinda hard to tell what he/she wants.
The truth is, there are so many different variations of GC and LC setups, and there are many different things you would be wanting to optimizing for when analyzing that this question is just super broad and kind of poor, at least how you are presenting it. At least, in my opinion.