Well the Iraq Survey group didn't find anything deployable. I recall that it was major news when they found a forgotten dump with a small quantity of old chemical artillery shells.
This is from Wikipedia which I accept isn't an unimpeachable source:
Throughout the life of ISG and SCP-B, there were only two occasions where chemical weapons were found. The first was a sarin mortar shell which had been reworked into a roadside improvised explosive device by insurgents. The second was a handful of 122-millimeter rocket warheads filled with inert mustard gas that was recovered near Babylon. Both were thought to be remainders from the Iran-Iraq War and were useless as offensive weapons. Both were later destroyed by ISG personnel. In late 2004 the ISG and the MCTs undertook some counter insurgency operations, although many details remain classified. There were other missions and organizations operating within the ISG which are Top Secret and are unlikely to be declassified anytime soon.