Determination of Several Halogenated Fumigants in Cereal Products by Steam Distillation and Capillary Gas Chromatography with Electron Capture Detection

Abstract

A steam distillation procedure is described for the determination of ethylene dibromide (EDB), ethylene dichloride (EDC), and carbon tetrachloride (CT) in flour, flour-based mixes, baked cakes, breakfast cereals, and citrus fruits. A representative sample is steam distilled using a modified Garman steam distillation apparatus, the steam and volatile components are condensed, and the condensate is partitioned with hexane (EDB) or pentane (EDC and CT). The solvent extract is then injected on-column and analyzed by using a 15 m X 0.32 mm 1.0 micron DB-1701 fused-silica capillary column at 50 degrees C for EDB or a 30 m X 0.25 mm 1.0 micron DB-5 column at 35 degrees C for EDC and CT. For routine EDB determinations as low as 10 ppb, 2 g flour, flour-based mix, or breakfast cereal is distilled and partitioned into 10 mL hexane. For enhanced sensitivity, up to 10 g dry sample can be concentrated into 1 mL hexane, for detection as low as 0.1 ppb (10% FSD, 2.0 pg). Recoveries from flour spiked with 100, 5, and 0.5 ppb EDB were 98.9, 95.1, and 117%, respectively. Coefficients of variation for marketplace flour samples found to contain EDB at 122, 6.0, and 1.2 ppb were 4.6, 6.9, and 3.6%, respectively, and for baby cereal at 0.22 ppb, 4.5%. Recoveries for EDC and CT from flour spiked at 46, 94, and 140 ppb were 61, 73, and 72%, and 96, 95, and 87%, respectively. Coefficients of variation were 10.0, 7.8, and 4.8, and 8.0, 3.2, and 8.4%, respectively.