Rapid and Convenient Potentiometric Method for Determining Fluorosulfate, a Byproduct of the Fumigant and Greenhouse Gas Sulfuryl Fluoride.

A fluorosulfate ion (FSO) is a hydrolysis product of sulfuryl fluoride (SOF), which is widely used to fumigate buildings, soil, construction materials, and postharvest commodities, and is a potent greenhouse gas. It is a potential marker for biological exposure to SOF and for monitoring the progress of reactions used to scrub SOF from fumigation vent gases. Here, we report a simple and inexpensive potentiometric method for determining FSO using a commercial nitrate-selective electrode and discuss its application. The method is suitable for solutions between 0.0025 mM and 660 mM FSO at initial pH between 5 and 9. Halide interference depends on its molar ratio to FSO and follows the sequence, F < Cl < Br ≪ I. Halide interference can be eliminated by adding silver sulfate. Interference by bicarbonate can be eliminated by HSO pretreatment, and interference by phosphate or pyrophosphate by MgSO addition. Sulfate does not interfere, as it does in ion chromatography. Satisfactory method detection limits for FSO in spiked aqueous extracts of 11 fruits were obtained. The method accurately quantified the yield of FSO relative to that of F in base hydrolysis of SOF. This study demonstrates that the developed method is highly selective, convenient, and sensitive and thus can be of great value in practice.