ASTM D5954-98(2014)e1

Standard Test Method for Mercury Sampling and Measurement in Natural Gas by Atomic Absorption Spectroscopy

SIGNIFICANCE AND USE
4.1 This test method can be used to measure the level of mercury in natural gas streams 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 natural gas processing and operation.  
4.2 Adsorption of the mercury on gold-coated beads can remove interferences associated with the direct measurement of mercury in natural gas. It preconcentrates the mercury before analysis thereby offering measurement of ultra-low average concentrations in a natural gas stream over a long span of time. It avoids the cumbersome use of liquid spargers with on-site sampling, and eliminates contamination problems associated with the use of potassium permanganate solutions.3,4,5
SCOPE
1.1 This test covers the determination of total mercury in natural gas at concentrations down to 1 ng/m3. It includes separate procedures for both sampling and atomic absorption spectrophotometric determination of mercury. The procedure detects both inorganic and organic forms of mercury.  
1.2 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 and/or mercury containing products into your state or country may be prohibited by law.  
1.4 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 use.

General Information

• Status: Historical
• Publication Date: 30-Nov-2006
• 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

Standards Content (Sample)

NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
Contact ASTM International (www.astm.org) for the latest information
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Designation: D5954 − 98 (Reapproved 2014)
Standard Test Method for
Mercury Sampling and Measurement in Natural Gas 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.
ε NOTE—Mercury caveat was added editorially to the Scope in April 2014.
1. Scope long path-length quartz cell connected to an atomic absorption
spectrophotometer. Mercury atoms are detected by measuring
1.1 This test covers the determination of total mercury in
3 their absorbance of light from a mercury source lamp at a
natural gas at concentrations down to 1 ng/m . It includes
characteristic wavelength. The mercury concentration is ob-
separate procedures for both sampling and atomic absorption
tained from the absorbance peak area by comparison to
spectrophotometric determination of mercury. The procedure
standards prepared at the time of analysis.
detects both inorganic and organic forms of mercury.
1.2 The values stated in SI units are to be regarded as the
4. Significance and Use
standard.
4.1 This test method can be used to measure the level of
1.3 Warning: Mercury has been designated by many regu-
mercury in natural gas streams for purposes such as determin-
latory agencies as a hazardous material that can cause serious
ing compliance with regulations, studying the effect of various
medical issues. Mercury, or its vapor, has been demonstrated to
abatement procedures on mercury emissions, checking the
be hazardous to health and corrosive to materials. Caution
validity of direct instrumental measurements, and verifying
should be taken when handling mercury and mercury contain-
that mercury concentrations are below those required for
ing products. See the applicable product Safety Data Sheet
natural gas processing and operation.
(SDS) for additional information. Users should be aware that
4.2 Adsorption of the mercury on gold-coated beads can
selling mercury and/or mercury containing products into your
remove interferences associated with the direct measurement
state or country may be prohibited by law.
of mercury in natural gas. It preconcentrates the mercury
1.4 This standard does not purport to address all of the
before analysis thereby offering measurement of ultra-low
safety concerns, if any, associated with its use. It is the
average concentrations in a natural gas stream over a long span
responsibility of the user of this standard to establish appro-
of time. It avoids the cumbersome use of liquid spargers with
priate safety and health practices and determine the applica-
on-site sampling, and eliminates contamination problems as-
bility of regulatory limitations prior to use. 3,4,5
sociated with the use of potassium permanganate solutions.
2. Referenced Documents
5. Apparatus
2.1 ASTM Standards:
5.1 Atomic Absorption Spectrophotometer, equipped with a
D1193 Specification for Reagent Water
10-cm-long path quartz absorption cell and a mercury source
lamp (EDLor other high intensity lamp). It must be capable of
3. Summary of Test Method
collecting and integrating data over a 30- to 60-s time window.
3.1 Mercury in a gas stream is adsorbed onto gold-coated
Background capabilities are strongly recommended.
silica beads and subsequently directly desorbed by heat into a
NOTE 1—Detection sensitivity may vary significantly depending on the
type of spectrophotometer and its accessories.
ThistestmethodisunderthejurisdictionofASTMCommitteeD03onGaseous
Fuels and is the direct responsibility of Subcommittee D03.05 on Determination of
Special Constituents of Gaseous Fuels.
Current edition approved Dec. 1, 2006. Published April 2014. Originally Schroeder,W.H.,“SamplingandAnalysisofMercuryanditsCompoundsinthe
approved in 1996. Last previous edition approved 2006 as D5954–98(2006). DOI: Atmosphere,” Environmental Science & Technology , 16, 1982, 394A–399A.
10.1520/D5954-98R14. Chao, S.S., andAttari,A., “Characterization and Measurements of Natural Gas
For referenced ASTM standards, visit the ASTM website, www.astm.org, or Trace Constituents—Volume II: Survey,” Final Report GRI-94/0243.2, June 1994.
contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM Braman, R.S., and Johnson, D.L., “Selective Absorption Tubes and Emission
Standards volume information, refer to the standard’s Document Summary page on Technique for the Determination of Ambient Forms of Mercury in Air,” Environ-
the ASTM website. mental Science & Technology, 8, 1974, pp. 996–1003.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
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D5954 − 98 (2014)
5.2 Rotameter or Other Flow Measurement Device capable sampling tube to the inlet port of the AAS cell. A Variac or
of attaining and regulating air at approximately 500 mL/min. other temperature control device may be required.
5.20 Stainless Steel 6-Port Switching Valve, ⁄8in.forcarrier
5.3 Rotameter or Other Flow Measurement Device capable
gas control (optional).
of attaining and regulating the natural gas sample at approxi-
mately 1000 to 2500 mL/min.
6. Reagents
5.4 Dry or Wet Positive Displacement Test Meter, or other
6.1 Purity of Reagents—Reagent grade chemicals shall be
calibrated total flow measurement device for measuring the
volume of the sample. used in all tests. Unless otherwise indicated, it is intended that
all reagents shall conform to the specifications of the Commit-
5.5 TFE-Fluorocarbon Tubing, to make connections to the
tee onAnalytical Reagents of theAmerican Chemical Society,
atomic absorption spectrophotometer. The size should be
where such specifications are available. Other grades may be
appropriate for the quartz absorption cell.
used, provided it is first ascertained that the reagent is of
5.6 Quartz Tubing, 12 cm long, ⁄4-in. outside diameter, to
sufficiently high purity to permit its use without lessening the
be used for sorbent (gold-coated silica) packing. accuracy of the determination.
6.2 Reagent Water—Reagent water, conforming to Type II
NOTE2—Allglassandplasticwarecomingintocontactwiththesample
must be acid washed with 20 % nitric acid and thoroughly rinsed with
of Specification D1193, shall be used for preparation of
water.
reagents and washing of the quartz tubing.
5.7 Quartz Tubing, approximately 24 in. long and 1-in.
6.3 Gold Chloride—Dissolve2gof gold chloride
outside diameter, to be used for the preparation of the gold-
(HAuCl ·3H O)inapproximately10mLofwater(Warning—
4 2
coated silica.
Poison).
5.8 Quartz Wool to be used for sorbent (gold-coated silica)
6.4 Sulfuric Acid, (concentrated, H SO , relative density
2 4
packing.
1.84) (Warning—Poison).
5.9 Fused Silica or Quartz Beads, 60/80 mesh, to be used
6.5 Nitric Acid, (concentrated, HNO , relative density 1.42)
for the preparation of the gold-coated silica.
(Warning—Poison).
5.10 Tube Furnace, approximately 8 to 10 cm in length, to
6.6 Nitric Acid, (20 %)—Mix 1 volume of concentrated
be used for the preparation of the gold-coated silica and the
nitric acid with 4 volumes of water.
mercury desorption. It must be capable of maintaining tem-
6.7 Mercury, triple distilled (Warning—Poison).
peratures up to 750 6 25°C over a 4-cm length. A Variac or
6.8 Mercury Standard Stock Solution, (1000 µg/mL)—
other temperature control device may be required.
Dissolve 1.080 g of mercury (II) oxide (HgO) in a minimal
NOTE 3—A shorter sampling tube and a shorter tube furnace may be
amount of HCl (1 + 1). Dilute to 1 L with water.
used as long as the specified temperature can be maintained.
6.9 Mercury Standard Intermediate Solution, (10 µg/mL)—
5.11 Silicone Tubing, ⁄4-in. inside diameter for connections.
Add 10.00 mL of the mercury standard stock solution to
1 1
5.12 Stainless Steel Tubing, ⁄4- and ⁄8-in outside diameter,
approximately 500 mL of water. Add 0.5 mL of concentrated
various lengths, for connections.
nitric acid and dilute to 1 L with water. Prepare this standard
solution daily.
5.13 Gastight Tube Fittings, ⁄4-in. nylon or TFE-
fluorocarbon construction, gastight end-cap type, plus one
6.10 Mercury Standard Working Solution, (100 ng/mL)—
stainless steel “T” fitting.
Add 1.00 mL of the mercury standard intermediate solution to
approximately 50 mL of water. Add 0.05 mL of concentrated
5.14 Precision Gastight Syringe, 500 µL, equipped with a
nitric acid and dilute to 100 mL with water. If micropipets are
needle with a side port opening.
not available, this standard may be prepared by serial dilution
NOTE 4—A digital syringe is recommended for better accuracy and
of the mercury standard intermediate solution. Prepare this
precision in calibration.
standard solution daily.
5.15 Septum Material, GC grade, low bleed type, made
6.11 Air, PP grade, or carbon filtered.
from silicone.
6.12 Hydrogen, PP grade (Warning—Flammable).
5.16 Water Bath or Constant Temperature Apparatus, ca-
6.13 Nitrogen, PP grade.
pable of regulating a sealed vial of mercury to 26 6 0.05°C.
6.14 Sulfur Impregnated Carbon,usedtofiltercarriergases.
5.17 Sealed Vial of Mercury, prepared from a 250-mL glass
bottle with a TFE-fluorocarbon septum cap and triple distilled
elemental mercury.
Reagent Chemicals, American Chemical Society Specifications , American
5.18 Thermocouple, for monitoring tube furnace tempera-
Chemical Society, Washington, DC. For suggestions on the testing of reagents not
tures.
listed by the American Chemical Society, see Analar Standards for Laboratory
Chemicals, BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopeia
5.19 Heating Tape, capable of maintaining a temperature of
and National Formulary, U.S. Pharmacopeial Convention, Inc. (USPC), Rockville,
50 to 60°C, to heat trace tubing from the outlet end of the MD.
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D5954 − 98 (2014)
7. Procedure for the Preparation of the Gold-Coated be filtered through HGR carbon and a clean tube packed with
Beads gold-coatedbeadstoremoveanytracesofmercurythatmaybe
present.
7.1 Soak the silica beads in concentrated sulfuric acid
overnighttoremoveanycoatingorcontamination.Silicabeads 8.6 Seal the end of each tube with a gastight fitting.
used for GC operations are often deactivated by silanization
and this coating must be removed. Wash thoroughly with 9. Sampling Procedure
reagent water and dry.
9.1 Two sampling tubes will be used, with the second tube
7.2 Add 50 g of acid washed silica beads to 10 mL of gold providing a check for breakthrough from the first tube. The
chloride solution. This will result in a 2 % loading of gold on
natural gas sample should flow from the sampling point (with
the silica substrate. Add a minimal amount of water, if a pressure regulator) into the first sampling tube (Tube 1),
necessary, to form a slurry. Heat on a hot plate with stirring
followed by the second tube (Tube 2), and finally the rotameter
until most of the water evaporates. Let the beads air-dry until flow control device.
the apparent moisture is evaporated. The color may change
9.2 The distance from the sampling point to the sampler
from yellow to a yellowish orange.
should be minimized because mercury is easily absorbed on
7.3 Pack the coated beads into the 1-in. outside diameter tubing lines and sampling equipment. The entire sampling
quartz tube with quartz wool plugs at either end and begin system must be passivated with the sample gas before any
heating using a tube furnace with a nitrogen purge. Slowly sampling, especially if low levels of mercury are expected.
raisethetemperaturefromambientto170°Ctodrythoroughly. Stainlesssteeltubingmustbeusedforconnectionsupstreamof
A heat gun may be used to remove condensed moisture the pressure regulator. High density TFE-fluorocarbon or
downstream of the furnace. The color of the beads will begin stainless steel tubing is preferred for connections downstream
to turn orange and then purplish. This may take 1 to2hto of the regulator. Flexible silicone tubing may be used to make
complete depending on how much moisture is present. short connections to sampling tubes. Any pumps, metering
valves, and so forth or other flow- and pressure-controlling
NOTE 5—Caution: Moisture and oxygen must be removed and the
devices should be located downstream of the sampler if
beads completely dry before hydrogen gas is introduced.
possible. The entire sampling line should be heated to prevent
7.4 Switch the gas to hydrogen and slowly raise the tem-
condensation, especially when a pressure reduction device is
perature to 250°C to reduce the gold ion to metallic gold. As
used to step down the pressure for sampling.
the temperature rises, HCl vapors are generated from the tube
9.3 Ascertain that the sample can be obtained at a pressure
and may appear as a smoky haze. A yellowish haze may be
not exceeding 15 psig (10 psig is preferable) and a flow of 1 to
seen on the inside walls of the quartz tube. The reaction is
2.5 L/min (2 L/min is preferable). Pressure- and flow-control
complete when this haze either disappears or does not change
devices may be required. A total flow volume measurement
over a 15- to 20-min period. Do not allow the temperature of
device, such as a dry test meter, can be used to record the exact
the furnace to rise above 250°C since gold chloride will
amounts of gas sampled for more accurate sampling.
sublimate at 265°C. This procedure may take 2 to3hto
complete.
9.4 Using a calibrated rotameter, installed upstream of the
total flow measurement device, determine an approximate flow
NOTE6—Caution:Thegasstreamexitingfromthetubefurnaceshould
control setting for the selected flow at the applied pressure.
be directed into a flask containing water to absorb the HCl gas generated
as the gold ion is reduced.
Thiswillsavetimewhensettingupthesamplingtubesandwill
condition the sampling system.
7.5 Raise the furnace temperature to approximately 400°C
over a 10-min period. Switch the gas to nitrogen and continue
9.5 Remove the fitting on one end of each tube and join the
heating up to 500 to 550°C for an additional 10 min. Remove
two tubes end-to-end with a short piece of silicone tubing.
the quartz tube from the furnace and allow to cool under the
9.6 Connect the back end of the sampling tube assembly
nitrogen purge.
(Tube 2) to the rotameter and connect the front end of the
sampling tube assembly (Tube 1) to the sampling point.
8. Procedure for the Preparation of the Sampling Tubes
Carefully open the sampling valve and quickly adjust the flow
8.1 Washeach ⁄4-in.outsidediameterquartztubewith20 %
control
...