Fumigant residues of carbon tetrachloride, ethylene dichloride, and ethylene dibromide in wheat, flour, bran, middlings, and bread

Berck, B.

Journal of Agricultural and Food Chemistry 22(6): 977-984


ISSN/ISBN: 0021-8561
PMID: 4430809
DOI: 10.1021/jf60196a024
Accession: 000384646

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Dowfume EB-5, consisting of carbon tetrachloride, ethylene dichloride and ethylene dibromide in 63:30:7 w/w proportions, was applied to 27.3 metric tons of wheat stored in a paper laminate bin. The distribution-persistence patterns of the compounds were monitored at 16 bin locations over a 14-day period by gas chromatography and hydrogen flame ionisation detection. Carbon tetrachloride gas concentrations were greatest at the bottom, the descending order of magnitude being bottom, middle, top and headspace. Ethylene dibromide gas concentrations, and those of ethylene dichloride to a lesser extent, were greatest in the headspace-top interface, the descending order of magnitude being the reverse of carbon tetrachloride. Fumigant residues in wheat, in the flour, bran and middlings derived from wheat and in bread baked from the flour were determined over a 7-week period of fumigant exposure by gas chromatography with electron capture detection. Amounts of unchanged carbon tetrachloride and ethylene dibromide as small as 0.01 ng could be detected. Residues of ethylene dichloride could not be satisfactorily removed or determined. or determined. Residues of the first two in the wheat varied, depending on the bin location and contact time, and ranged from 3.2 to 72.6 p.p.m. of carbon tetrachloride and from 0.0 to 3.3 p.p.m. of ethylene dibromide. Residues in bran and middlings were greater than those in flour. No residues of ethylene dibromide were found in any portion of the bread tested. Residues of carbon tetrachloride in bread ranged from 0 to 0.04 p.p.m.