Residual 1,2-dibromoethane in mango, capsicum, passionfruit and papaw after fumigation against Queensland fruit fly, Dacus tryoni (Froggatt).
Melksham K. J., Munro H. E.
Author Affiliation: Agricultural Chemistry Branch, Queensland Department of Primary Industries, Indooroopilly, Qld 4068, Australia.
Australian Journal of Experimental Agriculture 25 : 214-219
Abstract : Residual 1,2-dibromoethane was measured in mangoes, capsicums, passion fruits and pawpaws following fumigation at levels effective against Dacus tryoni. Post-fumigation forced-airing periods, storage conditions and times of storage were varied. The duration of the forced-airing period had no significant effect on the rate of dissipation of 1,2-dibromoethane from mangoes. Fumigated mangoes required storage at 21°C for at least 3 days before 1,2-dibromoethane levels fell below the maximum residue level (MRL) of 0.1 mg/kg. Cool storage of mangoes extended the time to at least 6 days. Fumigated capsicums stored at 21°C required 2 days and pawpaws at least 4 days. Even after storage for 7 days, 1,2-dibromoethane levels in passion fruits exceeded the MRL. A kinetic model was proposed that explained the behaviour of 1,2-dibromoethane in the various trials and in other literature reports. All samples were analysed by X-ray fluorescence spectrometry and many results were confirmed specifically and more sensitively by gas chromatography-mass spectrometry. The suitability of X-ray fluorescence for determining residual 1,2-dibromoethane was confirmed.