I recently nitrated around (~7mL) of glycerol through a process I have performed many times before. The nitroglycerin has been stored for ~3 weeks, and I noticed a drastic change in color from clear to an opaque dark green/blue.
I'm not sure exactly what occurred, but I am assuming some impurity in the final product was oxidized over the course of its storage. Most likely due to the fact that the container storing the fuming nitric acid I used for the nitration broke and the remaining acid was salvaged for this reaction.
Is there any chance the nitroglycerin could be unstable in its current state? I have not disturbed it and would like to dispose of it safely.