Phosphine emission measurements from a tobacco factory using cryogenic sampling and GC-ICP-MS analysis

Abstract

A cryosampling system together with a low temperature GC-ICP-MS method have been developed for the determination of phosphine for industrial hygiene purposes. The effect of sampling temperature on the collection efficiency of PH₃ was investigated. Two trapping mechanisms were differentiated for temperature ranges from −190 to −160 °C and from −110 to −35 °C. A cartridge filled with NaOH was used during the analytical desorption step to separate CO₂ from phosphine. Phosphine recovery was found to be better than 98% with peak area and retention times RSD values better than 4% and 2%, respectively. The use of a Nafion^® drying membrane before cryogenic trapping induced losses of PH₃ of about 15%. Sample conservation in a cryocontainer at −190 °C over a period of 15 days did not lead to significant losses of PH₃. For field experiments, air samples were collected in the fumigation room of a tobacco factory after fumigation, and outside the fumigation room during fumigation, using both cryogenic sampling and standard filters impregnated with silver nitrate. The results showed that phosphine concentrations in the tobacco factory were below the limit values for occupational exposure to phosphine (VME (France) and TLV-TWA (USA)) and also below the detection limit of the silver impregnated filter-ICP-AES method. Cryogenic trapping in combination with GC-ICP-MS allowed us to determine phosphine concentrations. The concentrations in ambient air are estimated to be about 1 ng m⁻³ and the detected concentrations in the vicinity of the fumigation room during the fumigation process are lower than 10 ng m⁻³.