Evaluation of Microwave Irradiation for Analysis of Carbonyl Sulfide, Carbon Disulfide, Cyanogen, Ethyl Formate, Methyl Bromide, Sulfuryl Fluoride, Propylene Oxide, and Phosphine in Hay

Abstract

Fumigant residues in hay were "extracted" by microwave irradiation. Hay, in gastight glass flasks, was placed in a domestic microwave oven, and fumigants were released into the headspace by microwave irradiation. Power settings for maximum release of fumigants were determined for carbonyl sulfide (COS), carbon disulfide (CS(2)), cyanogen (C(2)N(2)), ethyl formate (EF), methyl bromide (CH(3)Br), sulfuryl fluoride (SF), propylene oxide (PPO), and phosphine (PH(3)). Recoveries of fortified samples were >91% for COS, CS(2), CH(3)Br, SF, PPO, and PH(3) and >76% for C(2)N(2) and EF. Completeness of extraction was assessed from the amount of fumigant retained by the microwaved hay. This amount was determined from further microwave irradiation and was always small (<5% of the amount obtained from the initial procedure). Limits of quantification were <0.1 mg/kg for COS, CS(2), C(2)N(2), EF, and PH(3) and <0.5 mg/kg for CH(3)Br, SF, and PPO. These low limits were essentially due to the absence of interference from solvents and no necessity to inject large-volume gas samples. The microwave method is rapid and solvent-free. However, care is required in selecting the appropriate power setting. The safety implications of heating sealed flasks in microwave ovens should be noted.

Modeling post-fumigation desorption of phosphine in bulk stored grain

“…Phosphine remains the most widely used fumigant to treat bulk grains, oilseeds and pulses in each of the supply chain linkages from on-farm storage to grain terminals to overseas shipment, and accepted by international trade (Collins et al, 2000(Collins et al, , 2002Ren andMahon, 2006, 2007). However, two factors are challenging the fate of phosphine as a grain fumigant; 1) increasing resistance of insects, and 2) a Threshold Limit Value (TLV) of 0.3 ppm (USOSHA, 1988).…”

Phosphine fumigation and the ecology of the rust red flour beetle, Tribolium castaneum: the effects of phosphine resistance genes and sublethal exposure

“…Therefore fumigation of stored grain is the preferred method of chemical control. A number of alternative fumigants have been used, including hydrogen cyanide, sulfuryl fluoride, methyl iodide, methyl bromide, carbonyl sulphide and ethyl formate (Bell, 2000, Fields and White, 2002, Ren and Mahon, 2007, Zettler and Arthur, 2000. Before 2005, methyl bromide and phosphine were the only two licensed fumigants used world-wide against stored grain pests.…”