According to this CNN report (boldface mine):

Jordanian authorities said the attack would have mixed a combination of 71 lethal chemicals, which they said has never been done before, including blistering agents to cause third-degree burns, nerve gas and choking agents.

A Jordanian government scientist said the plot had been carefully worked out, with just the right amount of explosives to spread the deadly cloud without diminishing the effects of the chemicals. The blast would not burn up the poisonous chemicals but instead produce a toxic cloud, the scientist said, possibly spreading for a mile, maybe more.

The Jordanian intelligence buildings are within a mile of a large medical center, a shopping mall and a residential area.

"And there is no one combination of antidote to treat nerve agent, choking agent and blistering agent," the scientist said.

Cripes. I give good odds these idiots would have blown their own asses off just mixing this soup. I have seen other Jordanian sources that claimed the origin of these chemicals was Syria.

See also this post. Syria sure seems to have come into a lot of interesting material lately.