Forensic Chemical Studies on Drugs. I. Determination of Diquat and Paraquat in Aqueous Herbicide Preparations by Gas Chromatography

Abstract

A gas chromatographic method is described for determinig diquat (I) and paraquat (II), separately and simultaneously, in aqueous herbicide preparations. Analysis of I and II was performed by gas chromatography (detector : HFID) of their reduction products, which were derived by treatment with sodium borohydride. The ethyl acetate solutions of the reduction-products were injected into the gas chromatograph apparatus equipped with a glass column containing Gas-Chrom Z coated with 5% KOH and 5% PEG-6000 at 180° (usual determination) or 165° (simultaneous determination). These conditions were found to result in the satisfactory separation of the reduction products of I and II. This procedure is well suited forthe assay of 5-65 μg/ml concentration of I and II (internal standard substance : o-phenylenediamine). The main compounds isolated from the reduction-products of I and II were presumed on the basis of the results of nuclear magnetic resonance and mass spectra, and from elementary analysis to be N, N'-ethylene-1, 1', 2, 2', 3, 3', 6, 6'-octahydro-6, 6'-bipyridyl (III) and N, N'-dimethyl-1, 1', 2, 2', 3, 3', 6, 6'-octahydro-4, 4'-bipyridyl (IV), respectively.