How long can DNA last in room temperature?

Roughly speaking. Just imagine some small amount of DNA (we’re talking microliters here) diluted in water or TAE buffer in a microcentrifuge tube. How long can it last lying around the lab in room temperature before it denatures? I’m asking because my boss typically asks me to prepare things for him to do but he never ends up doing anything for a while. I doubt he’ll ever take it out on me if the DNA samples don’t do anything, but he always gets sidetracked and it takes him like 2 hours to finally use what I prepared for him.