Location: Commodity Protection and Quality Research
Project Number: 2034-43000-043-062-T
Project Type: Trust Fund Cooperative Agreement
Start Date: Jul 1, 2023
End Date: Dec 31, 2024
Objective:
To help agricultural trade by ensuring that U.S. agriculture will be able to continue to use the methyl bromide alternative, sulfuryl fluoride (SF), by: evaluating the accuracy of a popular device used to prevent bystander exposure to SF, and determine the magnitude of residues resulting from SF treatment of durable agricultural commodities.
Approach:
For the evaluation of the performance of the Spectros SF-ExplorIR portable sulfuryl fluoride monitoring device:
1. Commercial gas samples of approx. 200, 3 and 1 ppmv sulfuryl fluoride will be obtained. The 200 ppmv stock will be used to calibrate the response of a gas chromatograph with barrier ionization discharge detector (or equivalent) while the 3 and 1 ppm stocks will be used to verify the calibration.
2. SF-ExplorIR instruments provided by the cooperator will be purged with laboratory air and then used to measure tedlar bags containing 1.5L of 1 or 3 ppmv sulfuryl fluoride in air. For each tedlar bag sample prepared, 3 replicate measurements will be made by each ExplorIR. The concentration of sulfuryl fluoride in each tedlar bag will be confirmed by GC-BID before and after each set of ExplorIR readings.
Analytical methods for the analysis of fluoride and sulfuryl fluoride residues in the target commodities: corn, wheat, pistachios, and cocoa bean will be validated per European Union requirements.
1. For the analysis of sulfuryl fluoride residues, homogenized commodity will be transferred to a headspace vial and mixed with a solution of sodium chloride in water (brine). The headspace will be sampled by solid phase microextraction (SPME) and analyzed by gas chromatography coupled to mass spectrometry. For each commodity, the amount of solid, and brine as well as the SPME sampling conditions will be optimized.
2. For the analysis of fluoride residues, fluoride will be extracted using buffered water as an extraction solution and the analysis will be performed using a fluoride ion sensitive electrode. Alternate methods using a microwave muffle furnace to convert the organic material in a commodity to ash prior to extraction, or performing the analysis using a capillary electrophoresis system will also be examined and compared to the benchmark method in terms of sensitivity, ease of use and cost.
Magnitude of Residue Studies
1. Re-registration: The levels of sulfuryl fluoride and fluoride anion recovered from corn, wheat, pistachios, and cocoa bean when fumigated with sulfuryl fluoride at a dosage of 1500 g-h/m3 at 30°C ± 5°C will be determined.
