Something tells me we'd be better off knowing the long story to give you a really good and effective answer. If you're certain the room has been contaminated chemically then the chances are it is 3-Mercapto-3-methylbutan-1-ol, which has an odour similar to cat urine. All feline urine contains the chemical.
This chemical has a number of specific uses in laboratories so it's fairly easy to obtain. Furthermore, in most labs there's always one idiot who knows what the stuff smells like and has a great laugh wafting an unstoppered bottle under the nose of the unsuspecting. This chemical and its relatives have a tendency to disappear from labs mysteriously and end up in situations just as you describe
Anyhow, as far as getting rid of the smell is concerned, a couple of ideas come to mind. The most effective way of neutralising this smell is unquestionably via an enzymatic cleaner. I read a while ago about a product called Nature�s Miracle which is said to very effective for this sort of thing. Here�s a link discussing a number of the products:
http://www.naturemakesitwork.com/catalog/catal og.php?scat=Stain%20and%20odor%20removers
The products are marketed mostly in the USA but they are available from UK suppliers via the internet.
Another possibility is a range of products sold at the Pets At Home superstores in the UK and they may well do the job but I'm not certain if they contain enzymes. It would probably be best if you visited a store yourself and asked for advice. Here's the link:
http://www.petsathome.com/find/category-is-1+c at/category-is-1i+health+and+hygiene/category- is-1i01+cleaning/