METHOD 44 DETERMINATION OF REDUCED SULFUR GASES AND SULFUR DIOXIDE IN EFFLUENT SAMPLES BY GAS CHROMATOGRAPHIC METHOD

1.1 Effluent samples containing reduced sulfur gases and sulfur dioxide collected in Tedlar bag, Teflon bag or “SilcoCan ” canisters are analyzed using a gas chromatograph fitted with a flame photometric detector (FPD). 1.2 The reduced sulfur gases normally found in effluent samples are: hydrogen sulfide (H2S), carbonyl sulfide (COS), carbon disulfide (CS2), methyl mercaptan (MeSH), ethyl mercaptan (EtSH), and dimethyl sulfide (DMS). 1.3 The detection limit (LOD) of this method is 0.5 ppm (500 ppb) for all gases. 1.4 Interference: 1.4.1 The retention times of COS and SO2 are so close to each other that there is a possibility of one compound masking the other where the difference in their concentrations are so large with respect to each other. 1.4.2 High concentrations of hydrocarbon in the sample can have a quenching effect on the detector. 1.4.3 High concentrations (>10%) of carbon monoxide and carbon dioxide have desensitizing effect on the FPD. 1.5 This method combines the other methods for reduced sulfur determination found in the District’s Manual of Procedure, Volume III, into one. 2. APPARATUS 2.1 Gas Chromatograph (GC). This unit is fitted with a flame photometric detector (FPD), a sampling valve with a Teflon sample loop, a compatible integrator or a data station. The GC operating parameters are as follows