USEPA Method 16

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Semicontinuous Determination of Sulfur Emissions from Stationary Sources – USEPA Method 16

USEPA Method 16 is used for the determination of total reduced sulfur (TRS) compounds from recovery furnaces, lime kilns, and smelt dissolving tanks at kraft pulp mills and fuel gas combustion devices at petroleum refineries. The method is executed by extracting a gas sample from the emission source and analyzing an aliquot for hydrogen sulfide (H₂S), methyl mercaptan (MeSH), dimethyl sulfide (DMS), and dimethyl disulfide (DMDS) (known collectively as TRS) by gas chromatographic (GC) separation and flame photometric detection (FPD). SO₂ is removed selectively from the sample using a citrate buffer solution.

Since there are many systems or sets of operating conditions that represent useable methods of determining sulfur emissions, all systems which employ this principle, but differ only in details of equipment and operation, may be used as alternative methods, provided that the calibration precision and sample line loss criteria are met.

Moisture condensation in the sample delivery system, the analytical column, or the FPD burner block can cause losses or interferences. This is prevented by maintaining the probe, filter box, and connections at a temperature of at least 120 °C (248 °F). Moisture is removed in the SO₂ scrubber and heating the sample beyond this point is not necessary when the ambient temperature is above 0 °C (32 °F). Alternatively, moisture may be eliminated by heating the sample line, and by conditioning the sample with dry dilution air to lower its dew point below the operating temperature of the GC/FPD analytical system prior to analysis.

Carbon Monoxide (CO) and Carbon Dioxide (CO₂) have a substantial desensitizing effect on the flame photometric detector even after dilution. Acceptable systems must demonstrate that they have eliminated this interference by some procedure such as eluting these compounds before any of the compounds to be measured. Compliance with this requirement is demonstrated by submitting chromatograms of calibration gases with and without CO₂ in the diluent gas. The two chromatograms should show agreement within the precision limits described in the method.

Particulate matter in gas samples causes interference by eventual clogging of the analytical system. This interference is eliminated by using a Teflon filter after the probe.

Sulfur Dioxide (SO₂) is not a specific interferant but may be present in such large amounts that it cannot effectively be separated from the other compounds of interest. The SO₂ scrubber described in the method effectively removes SO₂ from the sample.

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Last Update: October 25, 2006