Pyrolysis analysis of the herbicide paraquat on cannabis by coupled gas chromatography-infrared spectroscopy.

Pyrolysis gas chromatography coupled with infrared identification of eluted peaks confirms that paraquat is pyrolyzed into chloromethane and 4,4'-dipyridyl at smoking temperatures and above. This reaction occurs at 610 degrees C to completion in small amounts in an inert atmosphere. The toxicity of 4,4'-dipyridyl remains to be determined. Pyrolysis of contaminated marijuana also produces the same two products, although detection at low limits is difficult with this procedure.