This test method can be used to determine the total mercury concentration of a natural gas stream down to 0.001 μg/m3. It can be used to assess compliance with environmental regulations, predict possible damage to gas plant equipment, and monitor the efficiency of mercury removal beds.
The preferred sampling method for mercury collection is on supported gold sorbent, which allows the element to be trapped and extracted from the interfering matrix of the gas. Thermal desorption of mercury is performed by raising the temperature of the trap by means of a nichrome wire coiled around it.
Since AFS demonstrates lower detection limits approaching 0.1 pg, this test method avoids difficulties associated with prolonged sampling time. Saturation of the trap with interferants such as hydrogen sulfide (H2S) is avoided. Average sampling can range between 15 to 30 min, or less.
1.1 This test method covers the determination of total mercury in natural gas streams down to 0.001 956;g/m3. It includes procedures to both obtaining a representative sample and the atomic fluorescence detection of the analyte. This procedure can be applied for both organic and inorganic mercury compounds.
1.2 Both, inch-pound and SI (metric) units of measurement are used throughout this standard.
1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to its use.
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