ASTM D5954-22a

Standard Test Method for Mercury Sampling and Measurement in Gaseous Fuels by Atomic Absorption Spectroscopy

SIGNIFICANCE AND USE
5.1 This test method can be used to measure the level of mercury in any gaseous fuel (as defined by Terminology D4150) for purposes such as determining compliance with regulations, studying the effect of various abatement procedures on mercury emissions, checking the validity of direct instrumental measurements, and verifying that mercury concentrations are below those required for gaseous fuel processing and operations.  
5.2 Adsorption of the mercury on gold-coated sorbent can remove interferences associated with the direct measurement of mercury in the presence of high concentrations of organic compounds. It preconcentrates the mercury before analysis, thereby offering measurement of ultra-low average concentrations in a gas stream over a long time span. It avoids the cumbersome use of liquid spargers with on-site sampling and eliminates contamination problems associated with the use of potassium permanganate solutions.5,6,7
SCOPE
1.1 This test method covers the determination of total mercury in gaseous fuels at concentrations down to 0.5 ng/m3. It includes separate procedures for both sampling and atomic absorption spectrophotometric determination of mercury. This procedure detects both inorganic and organic forms of mercury.  
1.2 Units—The values stated in SI units are to be regarded as the standard.  
1.3 Warning—Mercury has been designated by many regulatory agencies as a hazardous material that can cause serious medical issues. Mercury, or its vapor, has been demonstrated to be hazardous to health and corrosive to materials. Caution should be taken when handling mercury and mercury containing products. See the applicable product Safety Data Sheet (SDS) for additional information. Users should be aware that selling mercury or mercury containing products, or both, into your state or country may be prohibited by law.  
1.4 This standard does not purport to address all of the safety concerns associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.  
1.5 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

General Information

• Status: Published
• Publication Date: 31-Oct-2022
• ICS: 13.040.01 - Air quality in general
• ICS: 71.040.50 - Physicochemical methods of analysis
• ICS: 75.060 - Natural gas
• Technical Committee: D03 - Gaseous Fuels

Relations

• Refers: ASTM D4150-19 - Standard Terminology Relating to Gaseous Fuels
• Effective Date: 15-Dec-2019
• Refers: ASTM D4150-08(2016) - Standard Terminology Relating to Gaseous Fuels
• Effective Date: 01-Jul-2016
• Refers: ASTM D4150-08 - Standard Terminology Relating to Gaseous Fuels
• Effective Date: 01-Dec-2008
• Refers: ASTM D1193-06 - Standard Specification for Reagent Water
• Effective Date: 01-Mar-2006
• Refers: ASTM D4150-03 - Standard Terminology Relating to Gaseous Fuels
• Effective Date: 10-Aug-2003
• Refers: ASTM D4150-00 - Standard Terminology Relating to Gaseous Fuels
• Effective Date: 10-Jun-2000
• Refers: ASTM D1193-99 - Standard Specification for Reagent Water
• Effective Date: 10-Feb-1999
• Refers: ASTM D1193-99e1 - Standard Specification for Reagent Water
• Effective Date: 10-Feb-1999

Overview

ASTM D5954-22a is the internationally recognized standard test method for sampling and measuring mercury in gaseous fuels using atomic absorption spectroscopy (AAS). Published by ASTM International, this standard applies to a wide range of gaseous fuels, such as natural gas and renewable natural gas (RNG), providing accurate measurements down to concentrations of 0.5 ng/m³. The standard includes procedures for sample collection, preparation, and mercury quantification, making it a critical reference for compliance testing and process control in the energy sector.

Mercury is a hazardous pollutant found in trace amounts in gaseous fuels, and its measurement is vital for meeting regulatory requirements, protecting equipment, and ensuring environmental safety. This method leverages adsorption of mercury onto a gold-coated sorbent, which preconcentrates the analyte and reduces interferences from organic compounds, facilitating reliable detection of both inorganic and organic mercury species.

Key Topics

• Scope and Applicability: Suitable for measuring total mercury (inorganic and organic forms) in any gaseous fuel at ultra-trace levels.
• Sampling Method: Utilizes a two-tube system in series to prevent breakthrough and ensure quantitative mercury capture from gas streams.
• Analytical Technique: Employs atomic absorption spectroscopy (AAS) with thermal desorption and gold-coated sorbent tubes for high-sensitivity detection.
• Calibration: Provides calibration procedures using mercury sparging, mercury headspace, or aqueous standard solutions, supporting reliable quantification.
• Precision: An established single-laboratory precision of approximately 5%, with ongoing instrument calibration and quality control checks required.
• Safety Considerations: Addresses robust safety practices due to mercury's toxicity and outlines the importance of compliance with relevant regulations and safety data sheets (SDS).
• Interference Reduction: Gold-coated sorbent tubes minimize contamination and organic interference, providing a significant advantage over traditional liquid-based methods.

Applications

ASTM D5954-22a is widely adopted across several key areas in the gaseous fuels industry:

• Regulatory Compliance: Operators use this method to certify that mercury concentrations in compressed natural gas (CNG), natural gas, and RNG are within legal limits set by environmental authorities.
• Process Optimization: Gas processors and power generators monitor mercury to assess the effectiveness of abatement technologies and to prevent corrosion or poisoning of catalysts during gas treatment, liquefaction, or transportation.
• Validation and Verification: This standard is referenced for cross-checking direct instrumental mercury measurements and confirming results for reporting and traceability.
• Research and Development: Laboratories utilize the method for studying mercury behavior in different types and sources of gaseous fuels and for evaluating new emission control systems.

Related Standards

Several other standards and regulatory documents complement or are referenced within ASTM D5954-22a, including:

• ASTM D4150 - Terminology Relating to Gaseous Fuels, for consistent definitions across related standards.
• ASTM D1193 - Specification for Reagent Water, ensuring analytical water purity.
• USEPA Method 1631, Revision E - Mercury analysis in water using cold vapor atomic fluorescence spectrometry.
• 40 CFR Part 136 Appendix B - United States environmental criteria for method detection limits.
• General Quality Assurance Requirements - As outlined in Table 1, including calibration precision, breakthrough criteria, and spike recovery.

By following ASTM D5954-22a, users ensure accurate, reliable, and reproducible mercury measurements in gaseous fuels, supporting environmental compliance, operational safety, and effective process control.

Standards Content (Sample)

This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
Designation: D5954 − 22a
Standard Test Method for
Mercury Sampling and Measurement in Gaseous Fuels by
Atomic Absorption Spectroscopy
This standard is issued under the fixed designation D5954; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope D4150 Terminology Relating to Gaseous Fuels
2.2 USEPA Document:
1.1 This test method covers the determination of total
Method 1631, Revision E Mercury in Water by Oxidation,
mercury in gaseous fuels at concentrations down to 0.5 ng ⁄m .
Purge and Trap, and Cold Vapor Atomic Fluorescence
It includes separate procedures for both sampling and atomic
Spectrometry. EPA-821-R-02-019. U.S. Environmental
absorption spectrophotometric determination of mercury. This
Protection Agency, Office of Water, August 2002
procedure detects both inorganic and organic forms of mercury.
2.3 Other Document:
1.2 Units—The values stated in SI units are to be regarded
40 CFR Part 136 Appendix B Definition and Procedure for
as the standard.
the Determination of the Method Detection Limit, Revi-
1.3 Warning—Mercury has been designated by many regu-
sion 2, EPA Office of Water, EPA 821-R-16-006
latory agencies as a hazardous material that can cause serious
medical issues. Mercury, or its vapor, has been demonstrated to 3. Terminology
be hazardous to health and corrosive to materials. Caution
3.1 Definitions—For definitions of general terms used in
should be taken when handling mercury and mercury contain-
D03 Gaseous Fuels standards, refer to Terminology D4150.
ing products. See the applicable product Safety Data Sheet
3.2 Definitions of Terms Specific to This Standard:
(SDS) for additional information. Users should be aware that
3.2.1 Detection Limit, n—a statistically derived value rep-
selling mercury or mercury containing products, or both, into
resenting the lowest quantity of analyte that can confidently be
your state or country may be prohibited by law.
distinguished from background signal.
1.4 This standard does not purport to address all of the
3.2.2 Limit of Quantification, n—the lowest value of analyte
safety concerns associated with its use. It is the responsibility
which can be quantitatively described and is represented by the
of the user of this standard to establish appropriate safety,
lowest point on the calibration curve.
health, and environmental practices and determine the appli-
cability of regulatory limitations prior to use. 3.2.3 sorbent, n—a solid material that captures the analyte
1.5 This international standard was developed in accor- (mercury) from a gaseous source for quantitative analysis and
dance with internationally recognized principles on standard- is securely contained in sample tubes for sampling and
ization established in the Decision on Principles for the analysis.
Development of International Standards, Guides and Recom-
3.3 Abbreviations:
mendations issued by the World Trade Organization Technical
3.3.1 AAS—atomic absorption spectroscopy
Barriers to Trade (TBT) Committee.
3.3.2 EDL—electrodeless discharge lamp
2. Referenced Documents
3.3.3 PFA—perfluoroalkoxy
2.1 ASTM Standards:
3.3.4 TFE—tetrafluoroethylene
D1193 Specification for Reagent Water
4. Summary of Test Method
4.1 Mercury in a gas stream is adsorbed onto gold-coated
This test method is under the jurisdiction of ASTM Committee D03 on Gaseous
Fuels and is the direct responsibility of Subcommittee D03.06.02 on Analysis of sorbent and subsequently directly desorbed by heat into a long
Minor Constituents by Gas Chromatography.
path-length, inert cell connected to an atomic absorption
Current edition approved Nov. 1, 2022. Published November 2022. Originally
spectrophotometer. Mercury atoms are detected by measuring
approved in 1996. Last previous edition approved 2022 as D5954 – 22. DOI:
10.1520/D5954-22A.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM Available from United States Environmental Protection Agency (USEPA), 1200
Standards volume information, refer to the standard’s Document Summary page on Pennsylvania Ave., NW, Washington, DC 20460, https://www.epa.gov.
the ASTM website. Available from https://www.ecfr.gov.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D5954 − 22a
measured volume corrected for standard or normalized conditions.
their absorbance of light from a mercury source lamp at a
characteristic wavelength. Analyte mass is determined by
7.3 Rotameter or Other Flow Regulating Device, for
comparing the instrument response of the unknown sample to
calibration/analysis, capable of attaining and regulating gas
a response-versus-mass curve, generated daily from calibration
flow at approximately 500 mL/min.
standards.
7.4 TFE-Fluorocarbon Tubing, to make connections to the
atomic absorption spectrophotometer. The size should be
5. Significance and Use
appropriate for the absorption cell.
5.1 This test method can be used to measure the level of
7.5 Inert Push-to-Connect Fittings, various sizes, for con-
mercury in any gaseous fuel (as defined by Terminology
nections (materials such as perfluoroalkoxy (PFA), coated
D4150) for purposes such as determining compliance with
stainless steel, polypropylene, or TFE-Fluorocarbons).
regulations, studying the effect of various abatement proce-
7.5.1 Alternatively, silicone tubing with a ⁄4 in. inside
dures on mercury emissions, checking the validity of direct
diameter may be used for connections.
instrumental measurements, and verifying that mercury con-
1 1
centrations are below those required for gaseous fuel process-
7.6 Stainless Steel Tubing, ⁄4 and ⁄8 in. outside diameter
ing and operations.
with an inert coating on the interior (such as TFE-fluorocarbon
or fused-silica), various lengths, for connections.
5.2 Adsorption of the mercury on gold-coated sorbent can
remove interferences associated with the direct measurement
7.7 Gastight Tube Fittings, ⁄4 in. Nylon or TFE-
of mercury in the presence of high concentrations of organic
fluorocarbon construction, gastight end-cap type, plus one
compounds. It preconcentrates the mercury before analysis,
stainless steel “T” fitting.
thereby offering measurement of ultra-low average concentra-
7.8 Precision Gastight Syringes, various sizes, equipped
tions in a gas stream over a long time span. It avoids the
with a needle with a side port opening.
cumbersome use of liquid spargers with on-site sampling and
NOTE 3—A digital syringe is recommended for better accuracy and
eliminates contamination problems associated with the use of
5,6,7
precision in calibration.
potassium permanganate solutions.
7.9 Septum Material, GC grade, low bleed type, made from
6. Interferences
silicone.
6.1 The sorbent material does not retain compounds that
7.10 Water Bath or Constant Temperature Apparatus, ca-
interfere with sample analysis.
pable of regulating a sealed vial of mercury to 26 6 0.05 °C.
7.11 Sealed Vial of Mercury, prepared from a 250 mL glass
7. Apparatus
bottle with a TFE-fluorocarbon septum cap and triple distilled
7.1 Atomic Absorption Spectroscopy (AAS) Analyzer,
elemental mercury.
equipped with a long path-length, inert absorption cell and a
7.12 Heating Tape, capable of maintaining a temperature of
mercury source lamp (electrodeless discharge lamp (EDL) or
50 to 60 °C, to heat trace tubing from the outlet end of the
other high intensity lamp). The AAS should be capable of
sampling tube to the inlet port of the AAS cell. A variable AC
analyzing mercury using a thermal desorption furnace to heat
power supply or other temperature control device may be
the sample tubes to 550 °C. It must be capable of collecting and
required.
integrating data over a 30 to 60 s time window. Background
subtraction capabilities are strongly recommended. 1
7.13 Stainless Steel 6-Port Switching Valve, ⁄8 in. for carrier
gas control (optional).
NOTE 1—Detection sensitivity may vary significantly depending on the
type of spectrophotometer and its accessories.
7.14 Impinger, or equivalent sparging device with a mini-
7.2 Dry Test Meter or Other Flow Measurement Device, for
mum volume of 30 mL.
sampling, capable of attaining, regulating, and measuring gas
7.15 Volumetric Pipettes, micropipettes, or equivalent de-
flow at approximately 500 to 2500 mL ⁄min.
vices calibrated to deliver a known volume, assorted volumes.
7.2.1 A rotameter may be used in conjunction with a timing
device to measure air flow.
8. Reagents
NOTE 2—An air calibrated rotameter will not produce an accurate
8.1 Purity of Reagents—Reagent grade chemicals shall be
reading for gaseous fuel streams unless a correction factor is used,
used in all tests. Unless otherwise indicated, it is intended that
although a rotameter is suitable for controlling flow. To obtain an accurate
all reagents shall conform to the specifications of the Commit-
volume reading, a dry or wet gas flow meter is preferred. The gas flow
tee on Analytical Reagents of the American Chemical Society,
meter should be, and in some applications may be, required to be
where such specifications are available. Other grades may be
calibrated against a NIST-traceable reference gas flow meter, with
used, provided it is first ascertained that the reagent is of
Schroeder, W. H., “Sampling and Analysis of Mercury and its Compounds in
the Atmosphere,” Environmental Science & Technology, 16, 1982, 394A–399A. Reagent Chemicals, American Chemical Society Specifications, American
Chao, S. S., and Attari, A., “Characterization and Measurements of Natural Gas Chemical Society, Washington, DC. For suggestions on the testing of reagents not
Trace Constituents—Volume II: Survey,” Final Report GRI-94/0243.2. listed by the American Chemical Society, see Analar Standards for Laboratory
Braman, R. S., and Johnson, D. L., “Selective Absorption Tubes and Emission Chemicals, BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopeia
Technique for the Determination of Ambient Forms of Mercury in Air,” Environ- and National Formulary, U.S. Pharmacopeial Convention, Inc. (USPC), Rockville,
mental Science & Technology, 8, 1974, pp. 996–1003. MD.
D5954 − 22a
sufficiently high purity to permit its use without lessening the upstream of the pressure regulator. High density TFE-
accuracy of the determination. fluorocarbon or passivated stainless steel tubing is preferred for
connections downstream of the regulator. Inert push-to-connect
8.2 Reagent Water—Reagent water, conforming to Type II
fittings or flexible silicone tubing may be used to make short
of Specification D1193, shall be used for preparation of
connections to sampling tubes; although, the former is pre-
reagents and washing of the quartz tubing.
ferred. Any pumps or flow measurement devices should be
8.3 Sulfuric Acid, (concentrated, H SO , relative density
2 4
located downstream of the sampler. The entire sampling line
1.84) (Warning—Corrosive).
and the sample tubes should be heated above the dewpoint of
the sample stream to prevent condensation, especially when a
8.4 Nitric Acid, (concentrated, HNO , relative density 1.42)
(Warning—Corrosive). pressure reduction device is used to step down the pressure for
sampling.
8.5 Hydrochloric Acid, (concentrated, HCl, relative density
1.18). (Warning—Corrosive). 9.3 Ascertain that the sample can be obtained at a pressure
not exceeding 15 psig (10 psig is preferable) and a flow of 0.5
8.6 Mercury, triple distilled (Warning—Poison).
to 2.5 L/min. A pressure control device may be required in
8.7 Mercury Standard Stock Solution, (1000 μg/mL)—
addition to a flow measurement device.
Dissolve 1.080 g of mercury (II) oxide (HgO) in a minimal
9.3.1 It is possible to sample from ambient and sub-ambient
amount of HCl (1 + 1). Dilute to 1 L with water.
pressures using an appropriately designed extractive system to
8.8 Mercury Standard Intermediate Solution, (10 μg/mL)— measure and control flow. If sampling under these conditions,
Add 1.00 mL of the mercury standard stock solution to it may be necessary to sample at lower flows.
approximately 50 mL of water. Add 5 mL of concentrated
9.4 Determine an approximate flow control setting for the
nitric acid and dilute to 100 mL with water. This standard is
selected flow at the applied pressure. This will save time when
stable for 1 year in a tightly sealed glass or polypropylene
setting up the sampling tubes and will condition the sampling
container.
system.
8.9 Mercury Standard Working Solution, (100 ng ⁄mL)—
9.5 Remove the fitting on one end of each tube and join the
Add 1.00 mL of the mercury standard intermediate solution to
two tubes end-to-end with a short piece of silicone tubing or
approximately 50 mL of water. Add 5 mL of concentrated
inert push-to-connect fittings.
nitric acid and dilute to 100 mL with water. If micropipets are
9.6 Connect the back end of the sampling tube assembly
not available, this standard may be prepared by serial dilution
(Tube 2) to the flow measurement device and connect the front
of the mercury standard intermediate solution. Prepare this
end of the sampling tube assembly (Tube 1) to the sampling
standard solution daily.
point. Carefully open the sampling valve and quickly adjust the
NOTE 4—Alternatively, NIST traceable mercury standards at appropri-
flow control (and pressure if necessary) to obtain the required
ate concentrations may be purchased.
flow rate. Record the time and flow data at the start of
8.10 Stannous chloride solution prepared according to EPA
sampling. Mark the direction the sample gas flowed through
1631 Rev. E section 7.5. Alternatively, a concentrated stannous
the tube.
chloride solution may be purchased and diluted to a suitable
9.7 Flow the sample through the sampling tube for the
concentration. The solution should be made fresh daily from
desired amount of time, periodically checking that the flow is
reagents or from concentrate.
staying close to what it originally was and adjusting it if
NOTE 5—If mercury is present in the stannous chloride solution, sparge
necessary. Typical volumes of gas range from 50 to 1000 L. A
the solution with a clean gas source before use.
smaller volume of gas should be used for a sample containing
8.11 Air, PP grade, or carbon filtered.
a high concentration of mercury. The optimal range that should
be collected is between 2 and 300 ng of mercury. The capacity
8.12 Sulfur or Iodine Impregnated Carbon, used to filter
of the gold-coated silica sorbent is much higher than this,
carrier gases.
approximately 7 μg, but a loading at this level should be
avoided as the collection efficiency is lessened and the linearity
9. Sampling Procedure
of the atomic absorption spectrophotometer exceeded.
9.1 Two sampling tubes are used in series, with the second
tube providing a check for breakthrough from the first tube. 9.8 At the end of the sampling period, record the final time
and flow data, disconnect both tubes, and replace all of the
The gas sample should flow from the sampling point (with a
pressure regulator as necessary) into the first sampling tube endcaps tightly on the tubes. Securely attach a label to each of
the tubes, labeling the front tube as “Tube 1” and the back tube
(Tube 1), followed by the second tube (Tube 2), and finally the
flow measurement device. (connected to the flow measurement device) as “Tube 2.”
9.2 The distance from the sampling point to the sampler 9.9 Optionally, the sampling process can be modified to
should be minimized because mercury may be absorbed onto sample two pairs of sorbent tubes simultaneously and in
tubing lines and sampling equipment. The entire sampling parallel. Use a “T” fitting to divide the gas stream between two
system must be passivated with the sample gas before any sampling trains labelled “A” and “B.” By comparing the %RD
sampling, especially if low levels of mercury are expected. of the A and B trains of the run (see 12.2), the reproducibility
Passivated stainless steel tubing must be used for connections of the data can be assessed.
D5954 − 22a
9.10 Optionally, a field recovery test can be performed to sampling tubes using an air carrier gas at approximately
verify that the mercury in the matrix is recoverable within 500 mL ⁄min. Typical aliquot sizes range from 50 to 2000 μL
uncertainty and unaffected by interferents. Before sampling, which are delivered using a gastight syringe.
spike a known amount of mercury onto a sample tube (see 10.1 10.2.4 The gastight syringe is filled with air, and the needle
or 10.2). Prepare the sampling train as directed in 9.5 and 9.6 pushed through the seal of the vial containing elemental
with the spiked tube designated as “Tube 1” and an unspiked mercury. The syringe is pumped several times and allowed to
tube as “Tube 2.” Sample the spiked pair of tubes with an fill and equilibrate with mercury vapor for approximately 30 s.
unspiked pair, using the train described in 9.9. The syringe is withdrawn and the aliquot of mercury vapor is
9.10.1 If sampling the spiked pair and the unspiked pair injected onto the gold-coated silica sampling tube.
simultaneously is impossible, then sample the spiked pair 10.2.5 The injection is made using a gastight “T” fitting
immediately before or immediately after an unspiked pair and equipped with a silicone septum at one end of the quartz tube.
keep sampling conditions as similar as possible. It is important The septum is placed at a right angle with respect to the carrier
that the source concentration remains as close as possible gas entering directly in line with the tube. The syringe tip
between the spiked and unspiked runs because this concentra- should extend beyond the “T” and into the stream of air
tion is used as a constant when determining the spike recovery flowing into the sampling tube when an injection is made.
Quickly withdraw the syringe after the injection and let the air
(see calculation in 12.2.)
9.10.2 The amount of mercury spiked onto the sorbent tube flow for 90 s. Seal the ends of the tube with a gastight fitting
if the tube will not be immediately analyzed.
should be within 650 % of the expected capture.
10.2.6 The sealed mercury vial should be maintained at a
constant temperature that is carefully recorded and monitored.
10. Calibration Procedure
The temperature must be closely regulated because the vapor
10.1 Test Method A—Calibration Using Mercury Sparging:
pressure of mercury is very dependent on temperature. It is
10.1.1 This test method may be used if traceable measure-
critical that headspace temperature be at or below laboratory
ments are needed or if laboratories have safety concerns
temperature in order to prevent condensation of mercury inside
re
...

This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Because
it may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current version
of the standard as published by ASTM is to be considered the official document.
Designation: D5954 − 22 D5954 − 22a
Standard Test Method for
Mercury Sampling and Measurement in Gaseous Fuels by
Atomic Absorption Spectroscopy
This standard is issued under the fixed designation D5954; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope
1.1 This test method covers the determination of total mercury in gaseous fuels at concentrations down to 0.5 ng ⁄m . It includes
separate procedures for both sampling and atomic absorption spectrophotometric determination of mercury. This procedure detects
both inorganic and organic forms of mercury.
1.2 Units—The values stated in SI units are to be regarded as the standard.
1.3 Warning—Mercury has been designated by many regulatory agencies as a hazardous material that can cause serious medical
issues. Mercury, or its vapor, has been demonstrated to be hazardous to health and corrosive to materials. Caution should be taken
when handling mercury and mercury containing products. See the applicable product Safety Data Sheet (SDS) for additional
information. Users should be aware that selling mercury or mercury containing products, or both, into your state or country may
be prohibited by law.
1.4 This standard does not purport to address all of the safety concerns associated with its use. It is the responsibility of the
user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of
regulatory limitations prior to use.
1.5 This international standard was developed in accordance with internationally recognized principles on standardization
established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued
by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
2. Referenced Documents
2.1 ASTM Standards:
D1193 Specification for Reagent Water
D4150 Terminology Relating to Gaseous Fuels
2.2 USEPA Document:
Method 1631, Revision E Mercury in Water by Oxidation, Purge and Trap, and Cold Vapor Atomic Fluorescence Spectrometry.
EPA-821-R-02-019. U.S. Environmental Protection Agency, Office of Water, August 2002
This test method is under the jurisdiction of ASTM Committee D03 on Gaseous Fuels and is the direct responsibility of Subcommittee D03.05 on Determination of
Special Constituents of Gaseous Fuels.
Current edition approved June 1, 2022Nov. 1, 2022. Published June 2022November 2022. Originally approved in 1996. Last previous edition approved 20142022 as
ε1
D5954 – 98D5954 – 22.(2014) . DOI: 10.1520/D5954-22.10.1520/D5954-22A.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
Available from United States Environmental Protection Agency (USEPA), 1200 Pennsylvania Ave., NW, Washington, DC 20460, https://www.epa.gov.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D5954 − 22a
2.3 Other Document:
40 CFR Part 136 Appendix B Definition and Procedure for the Determination of the Method Detection Limit, Revision 2, EPA
Office of Water, EPA 821-R-16-006
3. Terminology
3.1 Definitions—For definitions of general terms used in D03 Gaseous Fuels standards, refer to Terminology D4150.
3.2 Definitions of Terms Specific to This Standard:
3.2.1 Detection Limit, n—a statistically derived value representing the lowest quantity of analyte that can confidently be
distinguished from background signal.
3.2.2 Limit of Quantification, n—the lowest value of analyte which can be quantitatively described and is represented by the lowest
point on the calibration curve.
3.2.3 sorbent, n—a solid material that captures the analyte (mercury) from a gaseous source for quantitative analysis and is
securely contained in sample tubes for sampling and analysis.
3.3 Abbreviations:
3.3.1 AAS—atomic absorption spectroscopy
3.3.2 EDL—electrodeless discharge lamp
3.3.3 PFA—perfluoroalkoxy
3.3.4 TFE—tetrafluoroethylene
4. Summary of Test Method
4.1 Mercury in a gas stream is adsorbed onto gold-coated sorbent and subsequently directly desorbed by heat into a long
path-length, inert cell connected to an atomic absorption spectrophotometer. Mercury atoms are detected by measuring their
absorbance of light from a mercury source lamp at a characteristic wavelength. Analyte mass is determined by comparing the
instrument response of the unknown sample to a response-versus-mass curve, generated daily from calibration standards.
5. Significance and Use
5.1 This test method can be used to measure the level of mercury in any gaseous fuel (as defined by Terminology D4150) for
purposes such as determining compliance with regulations, studying the effect of various abatement procedures on mercury
emissions, checking the validity of direct instrumental measurements, and verifying that mercury concentrations are below those
required for gaseous fuel processing and operations.
5.2 Adsorption of the mercury on gold-coated sorbent can remove interferences associated with the direct measurement of
mercury in the presence of high concentrations of organic compounds. It preconcentrates the mercury before analysis, thereby
offering measurement of ultra-low average concentrations in a gas stream over a long time span. It avoids the cumbersome use
of liquid spargers with on-site sampling and eliminates contamination problems associated with the use of potassium permanganate
5,6,7
solutions.
6. Interferences
6.1 The sorbent material does not retain compounds that interfere with sample analysis.
Available from https://www.ecfr.gov.
Schroeder, W. H., “Sampling and Analysis of Mercury and its Compounds in the Atmosphere,” Environmental Science & Technology, 16, 1982, 394A–399A.
Chao, S. S., and Attari, A., “Characterization and Measurements of Natural Gas Trace Constituents—Volume II: Survey,” Final Report GRI-94/0243.2.
Braman, R. S., and Johnson, D. L., “Selective Absorption Tubes and Emission Technique for the Determination of Ambient Forms of Mercury in Air,” Environmental
Science & Technology, 8, 1974, pp. 996–1003.
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7. Apparatus
7.1 Atomic Absorption Spectroscopy (AAS) Analyzer, equipped with a long path-length, inert absorption cell and a mercury source
lamp (electrodeless discharge lamp (EDL) or other high intensity lamp). The AAS should be capable of analyzing mercury using
a thermal desorption furnace to heat the sample tubes to 550 °C. It must be capable of collecting and integrating data over a 30
to 60 s time window. Background subtraction capabilities are strongly recommended.
NOTE 1—Detection sensitivity may vary significantly depending on the type of spectrophotometer and its accessories.
7.2 Dry Test Meter or Other Flow Measurement Device, for sampling, capable of attaining, regulating, and measuring gas flow
at approximately 500 to 2500 mL ⁄min.
7.2.1 A rotameter may be used in conjunction with a timing device to measure air flow.
7.2 Rotameter Dry Test Meter or Other Flow RegulatingMeasurement Device, for calibration/analysis,sampling, capable of
attaining attaining, regulating, and regulatingmeasuring gas flow at approximately 500 mL/min.to 2500 mL ⁄min.
7.2.1 A rotameter may be used in conjunction with a timing device to measure air flow.
NOTE 2—An air calibrated rotameter will not produce an accurate reading for gaseous fuel streams unless a correction factor is used, although a rotameter
is suitable for controlling flow. To obtain an accurate volume reading, a dry or wet gas flow meter is preferred. The gas flow meter should be, and in some
applications may be, required to be calibrated against a NIST-traceable reference gas flow meter, with measured volume corrected for standard or
normalized conditions.
7.3 Rotameter or Other Flow Regulating Device, for calibration/analysis, capable of attaining and regulating gas flow at
approximately 500 mL/min.
7.4 TFE-Fluorocarbon Tubing, to make connections to the atomic absorption spectrophotometer. The size should be appropriate
for the absorption cell.
7.5 Inert Push-to-Connect Fittings, various sizes, for connections (materials such as perfluoroalkoxyperfluoroalkoxy (PFA),
coated stainless steel, polypropylene, or TFE-Fluorocarbons).
7.5.1 Alternatively, silicone tubing with a ⁄4 in. inside diameter may be used for connections.
1 1
7.6 Stainless Steel Tubing, ⁄4 and ⁄8 in. outside diameter with an inert coating on the interior (such as TFE-fluorocarbon or
fused-silica), various lengths, for connections.
7.7 Gastight Tube Fittings, ⁄4 in. Nylon or TFE-fluorocarbon construction, gastight end-cap type, plus one stainless steel “T”
fitting.
7.8 Precision Gastight Syringes, various sizes, equipped with a needle with a side port opening.
NOTE 3—A digital syringe is recommended for better accuracy and precision in calibration.
7.9 Septum Material, GC grade, low bleed type, made from silicone.
7.10 Water Bath or Constant Temperature Apparatus, capable of regulating a sealed vial of mercury to 26 6 0.05 °C.
7.11 Sealed Vial of Mercury, prepared from a 250 mL glass bottle with a TFE-fluorocarbon septum cap and triple distilled
elemental mercury.
7.12 Heating Tape, capable of maintaining a temperature of 50 to 60 °C, to heat trace tubing from the outlet end of the sampling
tube to the inlet port of the AAS cell. A variable AC power supply or other temperature control device may be required.
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7.13 Stainless Steel 6-Port Switching Valve, ⁄8 in. for carrier gas control (optional).
7.14 Impinger, or equivalent sparging device with a minimum volume of 30 mL.
7.15 Volumetric Pipettes, micropipettes, or equivalent devices calibrated to deliver a known volume, assorted volumes.
8. Reagents
8.1 Purity of Reagents—Reagent grade chemicals shall be used in all tests. Unless otherwise indicated, it is intended that all
reagents shall conform to the specifications of the Committee on Analytical Reagents of the American Chemical Society, where
such specifications are available. Other grades may be used, provided it is first ascertained that the reagent is of sufficiently high
purity to permit its use without lessening the accuracy of the determination.
8.2 Reagent Water—Reagent water, conforming to Type II of Specification D1193, shall be used for preparation of reagents and
washing of the quartz tubing.
8.3 Sulfuric Acid, (concentrated, H SO , relative density 1.84) (Warning—Corrosive).
2 4
8.4 Nitric Acid, (concentrated, HNO , relative density 1.42) (Warning—Corrosive).
8.5 Hydrochloric Acid, (concentrated, HCl, relative density 1.18). (Warning—Corrosive).
8.6 Mercury, triple distilled (Warning—Poison).
8.7 Mercury Standard Stock Solution, (1000 μg/mL)—Dissolve 1.080 g of mercury (II) oxide (HgO) in a minimal amount of HCl
(1 + 1). Dilute to 1 L 1 L with water.
8.8 Mercury Standard Intermediate Solution, (10 μg/mL)—Add 1.00 mL of the mercury standard stock solution to approximately
50 mL 50 mL of water. Add 5 mL of concentrated nitric acid and dilute to 100 mL 100 mL with water. This standard is stable for
1 year in a tightly sealed glass or polypropylene container.
8.9 Mercury Standard Working Solution, (100(100 ng ng/mL)—Add ⁄mL)—Add 1.00 mL of the mercury standard intermediate
solution to approximately 50 mL of water. Add 5 mL of concentrated nitric acid and dilute to 100 mL with water. If micropipets
are not available, this standard may be prepared by serial dilution of the mercury standard intermediate solution. Prepare this
standard solution daily.
NOTE 4—Alternatively, NIST traceable mercury standards at appropriate concentrations may be purchased.
8.10 Stannous chloride solution prepared according to EPA 1631 Rev. E section 7.5. Alternatively, a concentrated stannous
chloride solution may be purchased and diluted to a suitable concentration. The solution should be made fresh daily from reagents
or from concentrate.
NOTE 5—If mercury is present in the stannous chloride solution, sparge the solution with a clean gas source before use.
8.11 Air, PP grade, or carbon filtered.
8.12 Sulfur or Iodine Impregnated Carbon, used to filter carrier gases.
Reagent Chemicals, American Chemical Society Specifications, , American Chemical Society, Washington, DC. For suggestions on the testing of reagents not listed by
the American Chemical Society, see Analar Standards for Laboratory Chemicals, BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopeia and National
Formulary, U.S. Pharmacopeial Convention, Inc. (USPC), Rockville, MD.
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9. Sampling Procedure
9.1 Two sampling tubes are used in series, with the second tube providing a check for breakthrough from the first tube. The gas
sample should flow from the sampling point (with a pressure regulator as necessary) into the first sampling tube (Tube 1), followed
by the second tube (Tube 2), and finally the flow measurement device.
9.2 The distance from the sampling point to the sampler should be minimized because mercury may be absorbed onto tubing lines
and sampling equipment. The entire sampling system must be passivated with the sample gas before any sampling, especially if
low levels of mercury are expected. Passivated stainless steel tubing must be used for connections upstream of the pressure
regulator. High density TFE-fluorocarbon or passivated stainless steel tubing is preferred for connections downstream of the
regulator. Inert push-to-connect fittings or flexible silicone tubing may be used to make short connections to sampling tubes;
although, the former is preferred. Any pumps or flow measurement devices should be located downstream of the sampler. The
entire sampling line and the sample tubes should be heated above the dewpoint of the sample stream to prevent condensation,
especially when a pressure reduction device is used to step down the pressure for sampling.
9.3 Ascertain that the sample can be obtained at a pressure not exceeding 15 psig (10 psig is preferable) and a flow of 0.5 to 2.5
L/min. A pressure control device may be required in addition to a flow measurement device.
9.3.1 It is possible to sample from ambient and sub-ambient pressures using an appropriately designed extractive system to
measure and control flow. If sampling under these conditions, it may be necessary to sample at lower flows.
9.4 Determine an approximate flow control setting for the selected flow at the applied pressure. This will save time when setting
up the sampling tubes and will condition the sampling system.
9.5 Remove the fitting on one end of each tube and join the two tubes end-to-end with a short piece of silicone tubing or inert
push-to-connect fittings.
9.6 Connect the back end of the sampling tube assembly (Tube 2) to the flow measurement device and connect the front end of
the sampling tube assembly (Tube 1) to the sampling point. Carefully open the sampling valve and quickly adjust the flow control
(and pressure if necessary) to obtain the required flow rate. Record the time and flow data at the start of sampling. Mark the
direction the sample gas flowed through the tube.
9.7 Flow the sample through the sampling tube for the desired amount of time, periodically checking that the flow is staying close
to what it originally was and adjusting it if necessary. Typical volumes of gas range from 50 to 1000 L. A smaller volume of gas
should be used for a sample containing a high concentration of mercury. The optimal range that should be collected is between
2 and 300 ng of mercury. The capacity of the gold-coated silica sorbent is much higher than this, approximately 7 μg, but a loading
at this level should be avoided as the collection efficiency is lessened and the linearity of the atomic absorption spectrophotometer
exceeded.
9.8 At the end of the sampling period, record the final time and flow data, disconnect both tubes, and replace all of the endcaps
tightly on the tubes. Securely attach a label to each of the tubes, labeling the front tube as “Tube 1” and the back tube (connected
to the flow measurement device) as “Tube 2.”
9.9 Optionally, the sampling process can be modified to sample two pairs of sorbent tubes simultaneously and in parallel. Use a
“T” fitting to divide the gas stream between two sampling trains labelled “A” and “B.” By comparing the %RD of the A and B
trains of the run (see 12.2), the reproducibility of the data can be assessed.
9.10 Optionally, a field recovery test can be performed to verify that the mercury in the matrix is recoverable within uncertainty
and unaffected by interferents. Before sampling, spike a known amount of mercury onto a sample tube (see 10.1 or 10.2). Prepare
the sampling train as directed in 9.5 and 9.6 with the spiked tube designated as “Tube 1” and an unspiked tube as “Tube 2.” Sample
the spiked pair of tubes with an unspiked pair, using the train described in 9.9.
9.10.1 If sampling the spiked pair and the unspiked pair simultaneously is impossible, then sample the spiked pair immediately
before or immediately after an unspiked pair and keep sampling conditions as similar as possible. It is important that the source
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concentration remains as close as possible between the spiked and unspiked runs because this concentration is used as a constant
when determining the spike recovery (see calculation in 12.2.)
9.10.2 The amount of mercury spiked onto the sorbent tube should be within 650 % of the expected capture.
10. Calibration Procedure
10.1 Test Method A—Calibration Using Mercury Sparging:
10.1.1 This test method may be used if traceable measurements are needed or if laboratories have safety concerns regarding the
storage of elemental mercury.
10.1.2 Build the sparging apparatus by connecting the air inlet of the impinger to a clean gas stream (nitrogen or air passed through
an activated carbon filter). Connect a baked-out sample tube to the impinger’s air outlet. Place about 5 to 10 mL of water in the
impinger. The impinger should have a minimum capacity of 30 mL.
10.1.3 All apparatus surfaces, including tubing, between the mercury-free gas source and the sample tube must be cleaned before
standards can be prepared. This is generally accomplished by adding a small volume of stannous chloride solution to the impinger
and passing the carrier gas through the system for 5 to 10 min at a flow rate of approximately 500 mL ⁄min.
10.1.4 Calibration standards are prepared using concentrations appropriate to the level of mercury collected on the sampling tube.
Different mercury loadings will require different volumes, different concentrations, or both, of the mercury working standard. Add
the mercury standard and a small amount of stannous chloride solution (about 0.5 mL) to the impinger. Sparge for at least 5 min
at a flow rate of approximately 500 to 1000 mL ⁄min. After sparging, seal the ends of the tubes with gastight fit
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