1 GAS CHROMATOGRAPHIC ANALYSIS OF THE STEREOISOMERS OF THE CHEMICAL WARFARE AGENT GF

Synthesis of the nerve agent cyclohexyl methylphosphonofluoridate (GF) yields a racemic mixture of two stereoisomers due to the presence of an asymmetric phosphorus atom. These two enantiomers, designated as P(+) and P(-), were separated in 8 minutes by chiral gas chromatography and quantified using flame photometric detection. Plots of peak area versus concentration of the individual enantiomers resulted in correlation coefficients greater than 0.99. The enantiomers were present in racemic GF in the ratio of 3:2 asP(-):P(+). The P(-) enantiomer was isolated using a method whereby the P(+) isomer was removed from the racemic mixture via preferential enzymatic catalyzed hydrolysis. The specific rotation of the P(-) enantiomer at 589 nm and 25 oC in methylene chloride was calculated to be –19.3o. The P(-) enantiomer also inhibited acetylcholinesterase more strongly than the racemic mixture, consistent with the findings for other optically active nerve agents.