Method 16C Approved for Total Reduced Sulfur (TRS) Emission Testing

On July 30, 2012, U.S. EPA announced that Method 16C is now an acceptable method for the measurement of total reduced sulfur (TRS) emissions.  One might ask, what is Method 16C, better yet, what compounds comprise TRS?  First, we’ll start with the definition of TRS.  TRS is comprised of the following four pollutants: hydrogen sulfide (H₂S), methyl mercaptan, dimethyl sulfide, and dimethyl disulfide.  Most of us associate TRS emissions with Kraft pulp mills and with its very characteristic odor.  Kraft pulp mills that are subject to 40 CFR Part 60 Subpart BB or petroleum refineries subject to 40 CFR Part 60 Subpart J, are required to periodically test for TRS.  In the past, three approved emission testing options were available for the measurement of TRS; Method 16, 16A, and 16B.  Method 16C combines components of existing Methods 16A (for TRS) and 6C (Determination of Sulfur Oxides from Stationary sources).  Sample gas is extracted from the stack through a heated probe and is then conditioned in a citrate buffer scrubber (as described in Method 16A).  From there, the sample gas is oxidized in a tube furnace, which converts the various TRS compounds to sulfur dioxide (SO₂).  The newly oxidized SO₂ is then analyzed using a real-time SO₂ analyzer (as in Method 6C).  The use of Method 16C for the testing of TRS is not required, just merely added as an alternative to the other available methods.