Deamination of Spermidine? I was making a solution of spermidine, and noticed that Sigma Aldrich warns that spermidine solutions deaminate over time. I tried to think of how that would happen, and made a diagram:



Assuming some of the spermidine has the secondary amine in an uncharged state, the lone pair electrons can attack either charged terminal amine group. I don't know which is more likely, I have drawn the 4 membered ring, but the other amine would make a 5 membered ring, which would probably be more stable. Either way, this would kick off an ammonia, which would be stable enough in water. Then a water molecule would attack a carbon on the ring and open it, making an OH2+ charged group, which would give up a proton. Of course the protons would be balanced because the ammonia would pick up a proton.

Does this make sense? It reminds me of nitrogen mustard chemistry, but must not be as reactive because spermidine is used to condense DNA, and nitrogen mustards are used to damage DNA. 

Additionally, spermidine seems hard to work with. I tried to make 10mL of a 10mM solution, and calculated what volume to use to get the right mass, because spermidine melts at 20-25C. However, when I used that volume, I had about 2.5 times as much mass as I wanted. I assume this is because the spermidine was not totally thawed out, and the density was higher than I assumed (925mg/mL at 25C). Has anyone worked with this compound and has suggestions for how to handle it better?
Here are some links to the mechanism of the degradation of spermidine and some analogues in living systems.


reference 1
reference 2
reference 3
reference 4


Based on these reactions I would guess that an oxidative pathway is followed here as well, once the sample has been exposed to air.  Instead of a nice enzyme catalyzed oxidation, here we would have a free radical oxidation. Here is a general outline of such a process.  The first step would involve generation 



of the more stable secondary nitrogen radical (as opposed to the primary terminal nitrogens) and formation of the nitrogen hydroperoxide.  Elimination of hydrogen peroxide could produce the two possible imines which could be further oxidized by oxygen to produce both possible diamines and both possible amino-aldehydes.  You could test your material for the presence of hydrogen peroxide, but the smell of putrescine ought to be a "dead" giveaway.