Acid Gas Monitoring in Stack Emissions

Gordon et al. used an IMS analyzer to study the rate of anission and volatilization of CIO2 and predict exposure to levels of CIO2 in ambient air. Levels of vapors 2 m from a large mixing tank containing concentrated solutions ( 200 to 860 ppm) were 1.4 ppmv as measured with a handheld analyzer. At 4 m, the level was decreased to 0.6 ppmv and fell below the OSH A permissible level at about 7 m. This and the application for emissions of bromine illustrate the best quantitative response with existing IMS instruments. 

The determination of HF using IMS should be fevored by electron affinity of HF but is complicated by overlap between the product ion peak for HF and the peak for the reactant ion, commonly O2. This was solved using methylsalicylate as a reagent gas methylsalicylate forms an adduct ion with 02 displacing the reactant ion peak to long drift times well displaced from that for HF. ° The product ion was described as (HF)3F and was well separated from the peak for methylsalicylate adduct to 02 . 

Interest in monitoring HF arises not only from occupational hygiene and environmental concerns but also from interests in HF as a precursor in the prodnction of chemical warfare agents. Thus, HF is considered a dual-use chemical and important within the sphere of counterterrorism. 

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