GH, also known a EA-1211, is an

organophosphate In organic chemistry, organophosphates (also known as phosphate esters, or OPEs) are a class of organophosphorus compounds with the general structure , a central phosphate molecule with alkyl or aromatic substituents. They can be considered a ...

nerve agent of the G-series.

References

G-series nerve agents Acetylcholinesterase inhibitors Methylphosphonofluoridates {{Organic-compound-stub