Determination of methyl bromide residues in stored foods using automated headspace gas chromatography

Abstract

An automated gas chromatographic headspace method capable of detecting methyl bromide (MB) down to 0.01 mg kg−1 has been developed and evaluated. The method is suitable for analysing cereals, nuts, seeds and dried fruit. Commodities are extracted with solvent and MB present is derivatised to methyl iodide (MI) which is determined by automated headspace gas chromatography. Results from the method described are compared with those using an established solvent extraction method and show good quantitative agreement. The analytical conditions recommended are likely to be suitable for examination of other commodities for MB residues.

Physical, chemical and environmental properties of selected chemical alternatives for the pre‐plant use of methyl bromide as soil fumigant

“…Air samples may be trapped in charcoal tubes and then desorbed with appropriate organic solvents followed by gas chromatography with electron capture detection. Similar approaches have been reported for residue determination in foods 25–28…”

The persistence of methyl bromide residues in rice, dried fruit, seeds and nuts following laboratory fumigation

“…The contents of the vial were swirled and allowed to stand for 1 h prior to analysis. Headspace vials were maintained at 60 °C for 15 min, pressurised with helium gas and the headspace contents transferred onto a DB624 capillary column for electron‐capture detection as described previously 6. Each commodity was sampled and analysed before conditioning, 2 h after fumigation and thereafter at seven day intervals.…”

“…However, general trends in the persistence of MB residues in the commodities studied should be applicable to all methods of treatment. The MB residue levels were monitored using a sensitive and automated gas chromatographic headspace method6 capable of detecting residues below action levels.…”