STATIC HEADSPACE AND GAS-CHROMATOGRAPHIC ANALYSIS OF FUMIGANT RESIDUES IN SOIL AND WATER

Soil fumigants are characterized by high vapor pressures and low boili ng points, which determine that the commonly used solvent extraction-b ased methods are not suitable for sample preparation. The paper report s static headspace gas chromatography (GC) methods for the analysis of the fumigants 1,3-dichloropropene (1,3-D) and methyl isothiocyanate ( MITC) in soil and water, Method optimization was achieved by modifying the sample matrix with concentrated salt solution and adjusting sampl e equilibration temperature and time on the headspace autosampler. The headspace GC methods' showed similar to 1. order of magnitude greater GC response than a cold solvent extraction method under the same GC c onditions and also gave cleaner chromatograms and more stable baseline s. When applied to soil samples taken from a fumigated field, the head spacee GC method showed reproducibility similar to that of a solvent e xtraction method but had an improved detectability fur deep-layer samp les that contained low levels of 1,3-D.