Doctoral Thesis
EXPLORATION OF SULFURYL FLUORIDE AND OZONE COMBINATIONS AS A FAST FUMIGANT FOR QUARANTINE PURPOSES AND MANAGEMENT OF PHOSPHINE RESISTANCE
Doctor of Philosophy (PhD), Murdoch University
2025
Abstract
Sulfuryl fluoride (SF) is now widely employed for control of structural, wood, and stored-product pests, particularly as a phosphine resistance breaker, under brand names such as Vikane® and ProFume®. SF decomposes to fluoride ions (F⁻), which are of concern to the accumulation of fluoride residues in foodstuffs and their related health impacts, including skeletal fluorosis and neurodevelopmental toxicity. While its fumigant action is well-characterised for a number of commodities, SF sorption/desorption and fluoride residue accumulation in Australian wheat are not well documented.
Experimental data indicated that SF sorption was non-linear in kinetics and concentration-dependent. At a lower dosage (4.5 mg/L), sorption was quick, as manifested by the strong reduction in gas concentration (C/C₀ = 0.42) following 7 days, demonstrating intense grain uptake. At a higher dosage (45 mg/L), sorption was less apparent (C/C₀ = 0.69). Desorption analysis showed SF is poorly adsorbed on wheat surfaces, allowing rapid release following fumigation. Over 99% of the SF taken up was released within 24 hours for both doses. SF was not detectable after Day 4 at the lower dose and Day 8 at the higher dose. Fluoride residue accumulation in wheat that had been fumigated was linearly dependent on the Ct (concentration × time) value applied. Low and high doses (4.5 and 45 mg/L for 7 days) produced 756 and 7,560 mg·h/L Ct values, respectively.
These results have practical implications for SF application in commercial warehouses. Fast sorption at low doses ensures effective pest control, while rapid desorption reduces residue hazards and downtime in operations. Fluoride buildup at high doses indicates the necessity for dose monitoring and control under high-workflow conditions. In conclusion, SF's kinetic profile, marked by rapid uptake and clearance, makes it an acceptable fumigant when applied within controlled situations. Its application at lower doses, particularly if combined with synergistic agents like ozone, can be an effective pest control strategy that maintains grain quality and manages food safety levels in Australian grain storage.
Details
- Title
- EXPLORATION OF SULFURYL FLUORIDE AND OZONE COMBINATIONS AS A FAST FUMIGANT FOR QUARANTINE PURPOSES AND MANAGEMENT OF PHOSPHINE RESISTANCE
- Authors/Creators
- Wenjuan Zhang
- Contributors
- Penghao Wang (Supervisor) - Murdoch University, Centre for Crop and Food InnovationYonglin Ren (Supervisor) - Murdoch University
- Awarding Institution
- Murdoch University; Doctor of Philosophy (PhD)
- Identifiers
- 991005821343407891
- Murdoch Affiliation
- School of Medical, Molecular and Forensic Sciences; College of Environmental and Life Sciences
- Resource Type
- Doctoral Thesis
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