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Evaluation of fluoride ion residue in sulfuryl fluoride (SF) fumigated Australian wheat

Zhang, Wenjuang (2021) Evaluation of fluoride ion residue in sulfuryl fluoride (SF) fumigated Australian wheat. Other thesis, Murdoch University.

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Sulfuryl fluoride (SF) is registered for the control of insect pests in stored grains and processed commodities. However, SF can break down to toxic fluoride ion residue in the fumigated commodities. This research aimed to understand the correlation between the sorption of sulfuryl fluoride (SF) and the levels of cumulative fluoride residue in Australian wheat. The accumulated fluoride residue was evaluated after multi-fumigation with SF.


Australia Standard White (ASW) wheat was collected from a farm in WA. The wheat samples were placed into one litre Erlenmeyer flasks (760±5 gram/flask) with a 90% filling ratio. The wheat samples were fumigated with sulphur fluoride (SF) at 45 mg/L (g/m3) dosage at 23°C and 60% RH for one week. After 0, 1, 2, 4, 7, 14 and 28 days’ aeration, twenty-five grams of the wheat samples with two replicates were grounded and digested in 0.1 M HNO3. Fluoride ion was detected and measured in SF fumigated wheat using a fluoride ion-selective electrode.


The calculated concentration × time (Ct) products were averaged at 5742 g·h·m-3. While the headspace concentration of SF decreased from 45 mg/L to 20 mg/L, in comparison with untreated wheat at a natural background level of 0.1 mg/L fluoride ion residue, SF fumigation has resulted in increased fluoride ion residue by 2.7, 2.8 and 3.8 mg/kg after the 1st, 2nd and 3rd SF fumigation treatments.


The fluoride found in Australian wheat was mainly due to SF fumigation at the post-harvest stage. The fluoride ion can accumulate owing to a repetition of SF treatments. The accumulated levels of fluoride ion may be elevated beyond the safety level, threatening consumer safety and human health.

Item Type: Thesis (Other)
Murdoch Affiliation(s): Agricultural Sciences
Notes: This is a Research Masters with Training thesis
Supervisor(s): Wang, Penghao and Ren, Yonglin
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