Liquid plant food

Hi all. I found a bottle of liquid plant food that I'd hardly used and it's about a year old. When I opened it today I took a sniff (don't ask, apparently I'm always smelling things!) and nearly burned my nostrils off by a strong smell of ammonia! The thing is, I don't remember it having such a smell when I first used it. It was a cheap brand and I could throw it away but that's still wasteful. 
Is that normal or am I inadvertently taking the first steps in Alchemy? 

Hello Jay, thanks for your reply. It's a dilutable Doff product for general use rated at 3.5-3.5-3.5. Is that good?  I'm better at pronouncing the chemicals than understanding their exact uses (joined this site for tips from you guys) so please excuse my ignorance lol.  Could it simply be that it hasn't been opened for a while? The bottle was stored in a cupboard near a radiator so it would have got slightly warm, so perhaps that contributed.

Could well be that one Lotuseed, although Jirble will doubtless know for sure! 

Cant find the Safety Data Sheet for that product, although their liquid tomato fertiliser is said to have an 'ammoniacal' odour, so I suppose there's a good chance that the general purpose one does too.

Not a good idea to store any liquid fertiliser either in a very warm or very light place (even Miracle grow granules fade in sunlight, although why they are blue to start off with is anyone's guess.)

At 3.5:3.5:3.5 it's a balanced fertiliser, which would be 'OK' for everything, but not ideal for some - leafy plants would benefit from higher nitrogen, flowering plants from higher potassium, for instance.

As I said before, it's unlikely to have degraded in such a way that it would actually damage anything you used it on, but if you're sure the ammonia smell is greater now than before it could well be that it won't be as effective as it should be.