Evaluation of fluoride ion residues in black tea after fumigation with sulfuryl fluoride

Abstract

Sulfuryl fluoride is a colorless, odorless gas used as a fumigant against pests during the storage of durable agricultural products. It is also one of the alternatives to methyl bromide, which is banned by the Montreal Protocol. During a fumigation, the decomposition product of sulfuryl fluoride residue can also be formed in addition to the sulfuryl fluoride residue. Fluoride is actually a natural ingredient of the tea plant. However, within the growing process of the tea plant fluoride is concentrated in the old leaves when compared with the young shoots. Investigating the variation of the fluoride content in black tea before and after sulfuryl fluoride fumigation is the subject of this study. Three different brands of black teas with different fluoride concentrations purchased from local supermarkets in 2022 were fumigated with approximately 60 g/m3 of sulfuryl fluoride for 24 hours in a 1 m3 fumigation chamber. The AOAC’s recommended method for extraction of fluoride in plants (Method 975.04) was applied in this study. It was compared with the fluoride contents after fumigation in teas (41.4; 165.1 and 329.5 mg/kg, respectively). It is concluded that there is no statistically [t(7)=0,284; t(7)=0,769 and t(7)=1,419 p>0,05] significant difference in fluoride content in teas after fumigation.