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Distribution and chemical fate of 36Cl-chlorine dioxide gas during the fumigation of tomatoes and cantaloupe

Smith, D. J., Ernst, W., Giddings, J. M.
Journal of agricultural and food chemistry 2014 v.62 no.48 pp. 11756
byproducts, cantaloupes, chemical residues, chlorine dioxide, fumigation, radiolabeling, seedbeds, tomatoes
The distribution and chemical fate of 36Cl-ClO2 gas subsequent to fumigation of tomatoes or cantaloupe was investigated as were major factors that affect the formation of chloroxyanion byproducts. Approximately 22% of the generated 36Cl-ClO2 was present on fumigated tomatoes after a 2 h exposure to approximately 5 mg of 36Cl-ClO2. A water rinse removed 14% of the radiochlorine while tomato homogenate contained ∼63% of the tomato radioactivity; 24% of the radiochlorine was present in the tomato stem scar area. Radioactivity in tomato homogenate consisted of 36Cl-chloride (≥80%), 36Cl-chlorate (5 to 19%), and perchlorate (0.5 to 1.4%). In cantaloupe, 55% of the generated 36Cl-ClO2 was present on melons fumigated with 100 mg of 36Cl-ClO2 for a 2 h period. Edible cantaloupe flesh contained no detectable radioactive residue (LOQ = 0.3 to 0.4 μg/g); >99.9% of radioactivity associated with cantaloupe was on the inedible rind, with <0.1% associated with the seed bed. Rind radioactivity was present as 36Cl-chloride (∼86%), chlorate (∼13%), and perchlorate (∼0.6%). Absent from tomatoes and cantaloupe were 36Cl-chlorite residues. Follow-up studies have shown that chlorate and perchlorate formation can be completely eliminated by protecting fumigation chambers from light sources.