ASTM D7623-20

Standard Test Method for Total Mercury in Crude Oil Using Combustion-Gold Amalgamation and Cold Vapor Atomic Absorption Method

SIGNIFICANCE AND USE
5.1 The emission of mercury during crude oil refining is an environmental concern. The emission of mercury may also contaminate refined products and form amalgams with metals, such as aluminum.  
5.2 When representative test portions are analyzed according to this procedure, the total mercury is representative of concentrations in the sample.
SCOPE
1.1 This test method covers the procedures to determine the total mercury content in a sample of crude oil.  
1.2 The test method may be applied to crude oil samples containing between 5 ng/mL to 400 ng/mL of mercury. The results may be converted to mass basis, and reported as ng/g of mercury.  
1.3 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.  
1.4 This work has been published in “Determination of Mercury in Crude Oil by Atomic Spectroscopy.”2  
1.5 WARNING—Mercury has been designated by many regulatory agencies as a hazardous substance that can cause serious medical issues. Mercury, or its vapor, has been demonstrated to be hazardous to health and corrosive to materials. Use Caution when handling mercury and mercury-containing products. See the applicable product Safety Data Sheet (SDS) for additional information. The potential exists that selling mercury or mercury-containing products, or both, is prohibited by local or national law. Users must determine legality of sales in their location.  
1.6 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, health, and environmental practices and determine the applicability of regulatory limitations prior to use.  
1.7 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-May-2020
• ICS: 75.040 - Crude petroleum
• Technical Committee: D02 - Petroleum Products, Liquid Fuels, and Lubricants
• Drafting Committee: D02.03 - Elemental Analysis

Relations

• Refers: ASTM D6300-24 - Standard Practice for Determination of Precision and Bias Data for Use in Test Methods for Petroleum Products, Liquid Fuels, and Lubricants
• Effective Date: 01-Mar-2024
• Refers: ASTM D4175-23a - Standard Terminology Relating to Petroleum Products, Liquid Fuels, and Lubricants
• Effective Date: 15-Dec-2023
• Refers: ASTM D6300-23a - Standard Practice for Determination of Precision and Bias Data for Use in Test Methods for Petroleum Products, Liquid Fuels, and Lubricants
• Effective Date: 01-Dec-2023
• Refers: ASTM D6299-23a - Standard Practice for Applying Statistical Quality Assurance and Control Charting Techniques to Evaluate Analytical Measurement System Performance
• Effective Date: 01-Dec-2023
• Refers: ASTM D6792-23c - Standard Practice for Quality Management Systems in Petroleum Products, Liquid Fuels, and Lubricants Testing Laboratories
• Effective Date: 01-Nov-2023
• Refers: ASTM D6792-23b - Standard Practice for Quality Management Systems in Petroleum Products, Liquid Fuels, and Lubricants Testing Laboratories
• Effective Date: 01-Oct-2023
• Refers: ASTM D4175-23e1 - Standard Terminology Relating to Petroleum Products, Liquid Fuels, and Lubricants
• Effective Date: 01-Jul-2023
• Refers: ASTM D6300-19a - Standard Practice for Determination of Precision and Bias Data for Use in Test Methods for Petroleum Products and Lubricants
• Effective Date: 01-Dec-2019
• Refers: ASTM D6299-17b - Standard Practice for Applying Statistical Quality Assurance and Control Charting Techniques to Evaluate Analytical Measurement System Performance
• Effective Date: 15-Dec-2017
• Refers: ASTM D6299-17a - Standard Practice for Applying Statistical Quality Assurance and Control Charting Techniques to Evaluate Analytical Measurement System Performance
• Effective Date: 15-Nov-2017
• Refers: ASTM D6299-17 - Standard Practice for Applying Statistical Quality Assurance and Control Charting Techniques to Evaluate Analytical Measurement System Performance
• Effective Date: 01-Jan-2017
• Refers: ASTM D6300-16 - Standard Practice for Determination of Precision and Bias Data for Use in Test Methods for Petroleum Products and Lubricants
• Effective Date: 01-Apr-2016
• Refers: ASTM D7482-15 - Standard Practice for Sampling, Storage, and Handling of Hydrocarbons for Mercury Analysis
• Effective Date: 01-Nov-2015
• Refers: ASTM D6300-15 - Standard Practice for Determination of Precision and Bias Data for Use in Test Methods for Petroleum Products and Lubricants
• Effective Date: 01-Jun-2015
• Refers: ASTM D7482-14 - Standard Practice for Sampling, Storage, and Handling of Hydrocarbons for Mercury Analysis
• Effective Date: 01-Oct-2014

Overview

ASTM D7623-20 sets out the standard test method for determining total mercury levels in crude oil, utilizing the combustion-gold amalgamation process combined with cold vapor atomic absorption spectroscopy. Developed by ASTM International, this method addresses a critical environmental and safety concern: the emission and presence of mercury in crude oil, which can contaminate refined petroleum products and create operational hazards during processing and storage.

Mercury detection and measurement in crude oil is essential for compliance with health, environmental, and product quality regulations. This standard covers how to accurately quantify the mercury content in crude oil samples in the range of 5 ng/mL to 400 ng/mL (results can be converted to a ng/g mass basis).

Key Topics

• Purpose and Scope:

  • Measures total mercury content in crude oil samples.
  • Applies to concentrations between 5 ng/mL and 400 ng/mL of mercury.
  • Results can be expressed in SI units (ng/mL or ng/g).

• Significance and Use:

  • Mercury present in crude oil can:
    • Be released as emissions during refining, with environmental consequences.
    • Contaminate refined products, causing further downstream challenges.
    • Form amalgams with metals (e.g., aluminum), leading to equipment corrosion.

• Analytical Procedure:

  • Crude oil sample is heated to liberate mercury.
  • Thermal and chemical decomposition occurs, followed by catalytic oxidation.
  • Mercury is trapped on gold amalgamator, then released and measured via cold vapor atomic absorption.
  • Provides quantification relative to certified reference standards.

• Health and Safety Considerations:

  • Mercury is highly toxic and regulated worldwide.
  • Contains explicit warnings on handling, storage, and potential legal restrictions.
  • Users must refer to Safety Data Sheets (SDS) and determine local regulatory requirements.

Applications

• Environmental Compliance:

  • Ensures crude oil processing facilities monitor and limit mercury emissions to meet regulatory requirements.

• Quality Assurance for Refined Products:

  • Provides data to prevent mercury contamination in fuels, lubricants, and other products.

• Operational Safety:

  • Helps prevent equipment failures by identifying mercury levels that could result in harmful amalgamation with metals.

• Laboratory Analysis:

  • Applicable for quality control and research laboratories conducting elemental analysis of petroleum products.

• Regulatory and Trade Requirements:

  • Supports compliance with local, national, and international standards regarding hazardous substances in petroleum.

Related Standards

• ASTM D4057 - Standard Practice for Manual Sampling of Petroleum and Petroleum Products
• ASTM D4175 - Terminology Relating to Petroleum Products, Liquid Fuels, and Lubricants
• ASTM D6792 - Practice for Quality Management Systems in Petroleum Products Testing Laboratories
• ASTM D7482 - Practice for Sampling, Storage, and Handling of Hydrocarbons for Mercury Analysis
• ASTM D1193 - Specification for Reagent Water

Practical Value

Implementing ASTM D7623-20 strengthens environmental stewardship and product safety within the oil industry. By standardizing mercury testing in crude oil, organizations can:

• Minimize environmental impact from mercury emissions.
• Protect equipment and personnel from the risks of mercury exposure.
• Meet increasingly stringent regulatory demands for pollution control and product quality.
• Rely on robust quality assurance practices aligned with internationally recognized methods.

For detailed procedures and compliance guidelines, users should consult the full ASTM D7623-20 standard, refer to referenced ASTM documents, and prioritize safety in all laboratory operations.

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: D7623 − 20
Standard Test Method for
Total Mercury in Crude Oil Using Combustion-Gold
Amalgamation and Cold Vapor Atomic Absorption Method
This standard is issued under the fixed designation D7623; 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* 2. Referenced Documents
1.1 This test method covers the procedures to determine the 2.1 ASTM Standards:
total mercury content in a sample of crude oil. D1193 Specification for Reagent Water
D4057 Practice for Manual Sampling of Petroleum and
1.2 The test method may be applied to crude oil samples
Petroleum Products
containing between 5 ng⁄mL to 400 ng⁄mL of mercury. The
D4175 Terminology Relating to Petroleum Products, Liquid
results may be converted to mass basis, and reported as ng/g of
Fuels, and Lubricants
mercury.
D4177 Practice for Automatic Sampling of Petroleum and
1.3 The values stated in SI units are to be regarded as
Petroleum Products
standard. No other units of measurement are included in this
D6299 Practice for Applying Statistical Quality Assurance
standard.
and Control Charting Techniques to Evaluate Analytical
Measurement System Performance
1.4 This work has been published in “Determination of
Mercury in Crude Oil by Atomic Spectroscopy.” D6300 Practice for Determination of Precision and Bias
Data for Use in Test Methods for Petroleum Products,
1.5 WARNING—Mercury has been designated by many
Liquid Fuels, and Lubricants
regulatory agencies as a hazardous substance that can cause
D6792 Practice for Quality Management Systems in Petro-
serious medical issues. Mercury, or its vapor, has been dem-
leum Products, Liquid Fuels, and Lubricants Testing
onstrated to be hazardous to health and corrosive to materials.
Laboratories
Use Caution when handling mercury and mercury-containing
D7482 Practice for Sampling, Storage, and Handling of
products. See the applicable product Safety Data Sheet (SDS)
Hydrocarbons for Mercury Analysis
for additional information. The potential exists that selling
D7622 Test Method for Total Mercury in Crude Oil Using
mercury or mercury-containing products, or both, is prohibited
Combustion and Direct Cold Vapor Atomic Absorption
by local or national law. Users must determine legality of sales
Method with Zeeman Background Correction
in their location.
1.6 This standard does not purport to address all of the
3. Terminology
safety concerns, if any, associated with its use. It is the
3.1 For definitions of terms used in this standard, refer to
responsibility of the user of this standard to establish appro-
Terminology D4175.
priate safety, health, and environmental practices and deter-
mine the applicability of regulatory limitations prior to use.
4. Summary of Test Method
1.7 This international standard was developed in accor-
4.1 Controlled heating of the analysis sample in oxygen is
dance with internationally recognized principles on standard-
usedtoliberatemercury.Thesampleisheatedtodrynessinthe
ization established in the Decision on Principles for the
instrument and then thermally (at about 700 °C) and chemi-
Development of International Standards, Guides and Recom-
cally decomposed. The decomposition products are carried by
mendations issued by the World Trade Organization Technical
flowing treated air to the catalytic section of the furnace (at
Barriers to Trade (TBT) Committee.
about 850 °C), where oxidation is completed. The decomposi-
tion products are carried to a gold amalgamator that selectively
This test method is under the jurisdiction of ASTM Committee D02 on
traps mercury. After the system is flushed with oxygen to
Petroleum Products, Liquid Fuels, and Lubricants and is the direct responsibility of
Subcommittee D02.03 on Elemental Analysis.
Current edition approved June 1, 2020. Published June 2020. Originally
approved in 2010. Last previous edition approved in 2015 as D7623 – 10 (2015). For referenced ASTM standards, visit the ASTM website, www.astm.org, or
DOI:10.1520/D7623-20. contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
Nadkarni, R.A. and Hwang, J. D., “Determination of Mercury in Crude Oil by Standards volume information, refer to the standard’s Document Summary page on
Atomic Spectroscopy” J. ASTM International, 8 (5), #1103559, (2011). the ASTM website.
*A Summary of Changes section appears at the end of this standard
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D7623 − 20
remove any remaining decomposition products other than 6.1.7 The light source for the atomic absorption process
mercury, the amalgamator is rapidly heated to about 600 °C, shall be a low pressure mercury lamp.
releasing mercury vapor. Flowing oxygen carries the mercury 6.1.8 A narrow bandpass interference filter or
vapor through absorbance cells positioned in the light path of monochromator, capable of isolating the 253.65 nm mercury
single wavelength cold vapor atomic absorption spectropho- line, shall be used.
tometer.Absorbance peak height or peak area, as a function of 6.1.9 The system may contain a computer for controlling
mercury concentration, is measured at 253.65 m. the various operations of the apparatus, for recording data, and
NOTE 1—Mercury and mercury salts can be volatized at low tempera-
for reporting results.
tures. Precautions against inadvertent mercury loss should be taken when
6.2 Analytical Balance, with a sensitivity of 0.1 mg.
using this test method.
6.3 Sample Combustion Boats, porcelain, quartz, or other
5. Significance and Use
material as recommended and of convenient size suitable for
use in the instrument being used.
5.1 The emission of mercury during crude oil refining is an
environmental concern. The emission of mercury may also
6.4 Crucibles, porcelain, high-form, 40 mL capacity or
contaminate refined products and form amalgams with metals,
suitable size for heating reagent in furnace.
such as aluminum.
6.5 Micropipettes, one or more units of variable volumes to
5.2 When representative test portions are analyzed accord-
cover a range of 10 µL to 250 µL. Appropriately sized tips
ing to this procedure, the total mercury is representative of
should also be available.
concentrations in the sample.
6.6 Ultrasonic Homogenizer—A bath type ultrasonic ho-
mogenizer is used to dissociate particulate mercury and thor-
6. Apparatus
oughly mix the sample.
6.1 There are several configurations of the instrumental
6.7 Electric Muffle Furnace, capable of maintaining 750 °C
components that can be used satisfactorily for this test
6 25 °C and sufficiently large to accommodate the sample
method. Functionally, the instrument shall have the following
boats and reagent containers.
components: sample heating furnace, decomposition furnace,
6.8 Glassware, class A, volumetric flasks and pipettes of
gold amalgamator, amalgamator furnace, measuring cuvettes,
mercury lamp, and detector. The following requirements are various capacities. All glassware must be thoroughly cleaned
with freshly prepared 10 % nitric acid solution and rinsed with
specified for all approved instruments.
water. It is recommended that dedicated glassware be main-
NOTE 2—Approval of an instrument with respect to these functions is
tained to minimize cross contamination.
paramount to this test method, since such approval tacitly provides
approval of both the materials and the procedures used with the system to
7. Sample
provide these functions.
7.1 Obtain the analysis sample of crude oil in accordance
6.1.1 The instrument shall be capable of drying the sample
with Practice D4057 or D4177. Crude oil should be collected
once it is weighed and introduced.
in a manner that ensures a representative sample from the bulk
6.1.2 The instrument shall have a decomposition tube,
container is obtained.
which shall be operated at a temperature high enough to
completely decompose the sample. The suggested operating
7.2 To prevent loss of mercury during storage and handling
temperature is at least 700 °C.
of samples, follow Practice D7482. Sample should not be
6.1.3 The catalyst shall be capable of completing the oxi-
collectedinmetalcontainers.Precleaned,glassvolatileorganic
dation of the sample and trapping halogens as well as nitrogen
analysis (VOA) vials have been found to be suitable for this
and sulfur oxides. The suggested operating temperature of the
purpose.
catalytic tube is 850 °C.
7.3 Samples should be analyzed as quickly as possible after
6.1.4 The instrument shall contain one or more gold amal-
collection. Sample containers should be kept tightly capped
gamator fixed to an inert material and shall be capable of
and stored in a cool location free from direct sunlight.
trapping all mercury.
6.1.5 The amalgamator shall contain a furnace capable of
8. Reagents
rapidlyheatingtheamalgamatortoreleasealltrappedmercury.
8.1 Purity of Reagents—Reagent grade chemicals shall be
6.1.6 The instrument shall have an absorption cell through
used in all tests. Unless otherwise indicated, it is intended that
which the elemental mercury released from the gold amalgam-
all reagents conform to the specifications of the Committee on
ator flows. The cell shall be heated to avoid any condensation
Analytical Reagents of the American Chemical Society where
of water or other decomposition products.
such specifications are available. Other grades may be used,
4 5
The sole source of supply of the apparatus known to the Committee at this time ACS Reagent Chemicals, Specifications and Procedures for Reagents and
is Nippon SP3D model available from Nippon Instrument Corp., 14-8,Akaoji-cho, Standard-Grade Reference Materials, American Chemical Society, Washington,
Takatsuki-shi, Osaka 569-1146, Japan. If you are aware of alternative suppliers, DC. For suggestions on the testing of reagents not listed by theAmerican Chemical
please provide this information to ASTM International Headquarters. Your com- Society, see Analar Standards for Laboratory Chemicals, BDH Ltd., Poole, Dorset,
ments will receive careful consideration at a meeting of the responsible technical U.K., and the United States Pharmacopeia and National Formulary, U.S. Pharma-
committee, which you may attend. copeial Convention, Inc. (USPC), Rockville, MD.
D7623 − 20
provided it is first ascertained that the reagent is of sufficiently solution prepared in accordance with 9.1. Fill to the mark with
high purity to permit use without lessening the accuracy of the L-cysteine solution and mix. This results in a mercury concen-
determination. tration of 100 mg⁄kg.
9.3 Working Standards Set—Prepare a set of mercury stan-
8.2 Purity of Water—Unless otherwise indicated, reference
dards that are appropriate to the range settings on the instru-
towatershallbeunderstoodtomeanreagentwaterconforming
ment in use. An example of such a set follows.
to Type II of Specification D1193. Water must be checked for
9.3.1 With a 5 mL pipette, transfer an aliquot of the mercu-
potential mercury contamination before use.
ric chloride stock solution to a 100 mL volumetric flask. Fill
8.3 Air or Oxygen—Filtered, purified air or high purity
the flask to the mark with L-cysteine solution and mix. This
oxygen, as specified by the instrument manufacturer, shall be
makes a 5 mg⁄kg standard.
used. The air must be mercury-free. Some instruments process
9.3.2 With a 1 mL pipette, transfer an aliquot of the mercu-
incomingcombustionairwithfiltersanddriersbeforeitisused
ric chloride stock solution to a 100 mLvolumetric flask and fill
for the analysis.
up to the mark with L-cysteine solution. Mix. This makes a
8.4 Certified Reference Materials (CRMs)—Use Certified
1 mg⁄kg standard.
Reference Material (CRM) crude oils with mercury values for
9.3.3 Perform appropriate dilutions of the 1 mg⁄kg standard
which confidence limits are issued by a recognized certifying
with L-cysteine solution to prepare 0.1 mg⁄kg and 0.01 mg⁄kg
agency such as the National Institute of Standards and Tech-
mercury standards.
nology (NIST).
10. Instrument Preparation
8.4.1 All CRMs, reference crude oils, or calibrating agents
10.1 Assemble the instrumental system in accordance with
must have precision values of less than or equal to method
the manufacturer’s instructions. Follow the instrument manu-
repeatability. Such CRMS, reference crude oils, or calibrating
facturer’s recommended procedure to optimize the perfor-
agents must be stable and must be mixed thoroughly before
mance of the instrument.
each use.
10.2 Choosethepropersensitivityrangeandsampleheating
8.5 L-cysteine, 99+ % purity. Reagents must be evaluated
mode based upon the expected mercury concentration and the
for mercury content by checking blank solutions for response
sample matrix.
on the instrument.
10.3 Reagents used for the analysis of hydrocarbon samples
8.6 Nitric Acid, concentrated, Trace Metal Grade or better.
should be placed in the 750 °C muffle furnace overnight prior
8.7 Mercuric Chloride, 99.99+ % purity. A commercially
to use. Sample boats should also be pretreated in the muffle
prepared mercury stock standard may be used.
furnace before initial use.
8.8 Phosphate Buffer, pH 7.2. Some phosphate buffers use
10.4 The instrument should be run through several heating
mercury compounds as preservative. The buffer must be
cycles after being powered up to attain a new blank signal. A
mercury-free. Check with the instrument manufacturer for
satisfactory blank should have stable response and a signal that
sources of suitable buffer.
corresponds to the equivalent of <0.1 ng⁄g mercury in the
sample.
8.9 Combustion Reagents:
8.9.1 Additive 1 or B (Aluminum Oxide), ground, available
11. Calibration Procedure
from instrument manufacturer.
11.1 Choose the work
...

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: D7623 − 10 (Reapproved 2015) D7623 − 20
Standard Test Method for
Total Mercury in Crude Oil Using Combustion-Gold
Amalgamation and Cold Vapor Atomic Absorption Method
This standard is issued under the fixed designation D7623; 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 Scope*
1.1 This test method covers the procedures to determine the total mercury content in a sample of crude oil.
1.2 The test method may be applied to crude oil samples containing between 5 ng ⁄mL to 400 ng ⁄mL of mercury. The results
may be converted to mass basis, and reported as ng/g of mercury.
1.3 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
1.4 This work has been published in “Determination of Mercury in Crude Oil by Atomic Spectroscopy.”
1.5 WARNING—Mercury has been designated by many regulatory agencies as a hazardous materialsubstance that can cause
central nervous system, kidney and liver damage. serious medical issues. Mercury, or its vapor, may has been demonstrated to be
hazardous to health and corrosive to materials. Caution should be taken Use Caution when handling mercury and mercury
containing mercury-containing products. See the applicable product Material Safety Data Sheet (MSDS) for details and EPA’s
website—http://www.epa.gov/mercury/faq.htm—for additional information. Users should be aware (SDS) for additional informa-
tion. The potential exists that selling mercury and/or mercury containing products into your state or country may be prohibited by
law.or mercury-containing products, or both, is prohibited by local or national law. Users must determine legality of sales in their
location.
1.6 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 safety, health, and healthenvironmental practices and determine the
applicability of regulatory limitations prior to use.
1.7 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
D4057 Practice for Manual Sampling of Petroleum and Petroleum Products
D4175 Terminology Relating to Petroleum Products, Liquid Fuels, and Lubricants
D4177 Practice for Automatic Sampling of Petroleum and Petroleum Products
D6299 Practice for Applying Statistical Quality Assurance and Control Charting Techniques to Evaluate Analytical Measure-
ment System Performance
D6300 Practice for Determination of Precision and Bias Data for Use in Test Methods for Petroleum Products, Liquid Fuels, and
Lubricants
D6792 Practice for Quality Management Systems in Petroleum Products, Liquid Fuels, and Lubricants Testing Laboratories
D7482 Practice for Sampling, Storage, and Handling of Hydrocarbons for Mercury Analysis
This test method is under the jurisdiction of ASTM Committee D02 on Petroleum Products, Liquid Fuels, and Lubricants and is the direct responsibility of Subcommittee
D02.03 on Elemental Analysis.
Current edition approved April 1, 2015June 1, 2020. Published June 2015June 2020. Originally approved in 2010. Last previous edition approved in 20102015 as
D7623 – 10.D7623 – 10 (2015). DOI:10.1520/D7623-10R15.DOI:10.1520/D7623-20.
Nadkarni, R. A. and Hwang, J. D., “Determination of Mercury in Crude Oil by Atomic Spectroscopy” J. ASTM International, 8 (5), #1103559, (2011).
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.
*A Summary of Changes section appears at the end of this standard
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D7623 − 20
D7622 Test Method for Total Mercury in Crude Oil Using Combustion and Direct Cold Vapor Atomic Absorption Method with
Zeeman Background Correction
3. Terminology
3.1 For definitions of terms used in this standard, refer to Terminology D4175.
4. Summary of Test Method
4.1 Controlled heating of the analysis sample in oxygen is used to liberate mercury. The sample is heated to dryness in the
instrument and then thermally (at about 700 °C) and chemically decomposed. The decomposition products are carried by flowing
treated air to the catalytic section of the furnace (at about 850 °C), where oxidation is completed. The decomposition products are
carried to a gold amalgamator that selectively traps mercury. After the system is flushed with oxygen to remove any remaining
decomposition products other than mercury, the amalgamator is rapidly heated to about 600 °C, releasing mercury vapor. Flowing
oxygen carries the mercury vapor through absorbance cells positioned in the light path of single wavelength cold vapor atomic
absorption spectrophotometer. Absorbance peak height or peak area, as a function of mercury concentration, is measured at
253.65 m.
NOTE 1—Mercury and mercury salts can be volatized at low temperatures. Precautions against inadvertent mercury loss should be taken when using
this test method.
5. Significance and Use
5.1 The emission of mercury during crude oil refining is an environmental concern. The emission of mercury may also
contaminate refined products and form amalgams with metals, such as aluminum.
5.2 When representative test portions are analyzed according to this procedure, the total mercury is representative of
concentrations in the sample.
6. Apparatus
6.1 There are several configurations of the instrumental components that can be used satisfactorily for this test method.
Functionally, the instrument shall have the following components: sample heating furnace, decomposition furnace, gold
amalgamator, amalgamator furnace, measuring cuvettes, mercury lamp, and detector. The following requirements are specified for
all approved instruments.
NOTE 2—Approval of an instrument with respect to these functions is paramount to this test method, since such approval tacitly provides approval of
both the materials and the procedures used with the system to provide these functions.
6.1.1 The instrument shall be capable of drying the sample once it is weighed and introduced.
6.1.2 The instrument shall have a decomposition tube, which shall be operated at a temperature high enough to completely
decompose the sample. The suggested operating temperature is at least 700 °C.
6.1.3 The catalyst shall be capable of completing the oxidation of the sample and trapping halogens as well as nitrogen and
sulfur oxides. The suggested operating temperature of the catalytic tube is 850 °C.
6.1.4 The instrument shall contain one or more gold amalgamator fixed to an inert material and shall be capable of trapping all
mercury.
6.1.5 The amalgamator shall contain a furnace capable of rapidly heating the amalgamator to release all trapped mercury.
6.1.6 The instrument shall have an absorption cell through which the elemental mercury released from the gold amalgamator
flows. The cell shall be heated to avoid any condensation of water or other decomposition products.
6.1.7 The light source for the atomic absorption process shall be a low pressure mercury lamp.
6.1.8 A narrow bandpass interference filter or monochromator, capable of isolating the 253.65 nm mercury line, shall be used.
6.1.9 The system may contain a computer for controlling the various operations of the apparatus, for recording data, and for
reporting results.
6.2 Analytical Balance, with a sensitivity of 0.1 mg.
6.3 Sample Combustion Boats, porcelain, quartz, or other material as recommended and of convenient size suitable for use in
the instrument being used.
6.4 Crucibles, porcelain, high-form, 40 mL capacity or suitable size for heating reagent in furnace.
6.5 Micropipettes, one or more units of variable volumes to cover a range of 10 μL to 250 μL. Appropriately sized tips should
also be available.
The sole source of supply of the apparatus known to the Committee at this time is Nippon SP3D model available from Nippon Instrument Corp., 14-8, Akaoji-cho,
Takatsuki-shi, Osaka 569-1146, Japan. If you are aware of alternative suppliers, please provide this information to ASTM International Headquarters. Your comments will
receive careful consideration at a meeting of the responsible technical committee, which you may attend.
D7623 − 20
6.6 Ultrasonic Homogenizer—A bath type ultrasonic homogenizer is used to dissociate particulate mercury and thoroughly mix
the sample.
6.7 Electric Muffle Furnace, capable of maintaining 750 °C 6 25 °C and sufficiently large to accommodate the sample boats
and reagent containers.
6.8 Glassware, class A, volumetric flasks and pipettes of various capacities. All glassware must be thoroughly cleaned with
freshly prepared 10 % nitric acid solution and rinsed with water. It is recommended that dedicated glassware be maintained to
minimize cross contamination.
7. Sample
7.1 Obtain the analysis sample of crude oil in accordance with Practice D4057 or D4177. Crude oil should be collected in a
manner that ensures a representative sample from the bulk container is obtained.
7.2 To prevent loss of mercury during storage and handling of samples, follow Practice D7482. Sample should not be collected
in metal containers. Precleaned, glass volatile organic analysis (VOA) vials have been found to be suitable for this purpose.
7.3 Samples should be analyzed as quickly as possible after collection. Sample containers should be kept tightly capped and
stored in a cool location free from direct sunlight.
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 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 use without lessening the accuracy of the determination.
8.2 Purity of Water—Unless otherwise indicated, reference to water shall be understood to mean reagent water conforming to
Type II of Specification D1193. Water must be checked for potential mercury contamination before use.
8.3 Air or Oxygen—Filtered, purified air or high purity oxygen, as specified by the instrument manufacturer, shall be used. The
air must be mercury-free. Some instruments process incoming combustion air with filters and driers before it is used for the
analysis.
8.4 Certified Reference Materials (CRMs)—Use Certified Reference Material (CRM) crude oils with mercury values for which
confidence limits are issued by a recognized certifying agency such as the National Institute of Standards and Technology (NIST).
8.4.1 All CRMs, reference crude oils, or calibrating agents must have precision values of less than or equal to method
repeatability. Such CRMS, reference crude oils, or calibrating agents must be stable and must be mixed thoroughly before each
use.
8.5 L-cysteine, 99+ % purity. Reagents must be evaluated for mercury content by checking blank solutions for response on the
instrument.
8.6 Nitric Acid, concentrated, Trace Metal Grade or better.
8.7 Mercuric Chloride, 99.99+ % purity. A commercially prepared mercury stock standard may be used.
8.8 Phosphate Buffer, pH 7.2. Some phosphate buffers use mercury compounds as preservative. The buffer must be
mercury-free. Check with the instrument manufacturer for sources of suitable buffer.
8.9 Combustion Reagents:
8.9.1 Additive 1 or B (Aluminum Oxide), ground, available from instrument manufacturer.
8.9.2 Additive 2 or M, 40/60 m % mixture of calcium hydroxide and sodium carbonate available from instrument manufacturer.
8.9.3 Calcium Hydroxide, 99.5 % minimum purity.
8.9.4 Sodium Carbonate, 99.99 % minimum purity.
8.10 Glassine Weighing Paper.
9. Preparation of Mercury Standards
9.1 L-cysteine Solution, 0.001 m %—Weigh approximately 0.010 g of L-cysteine to the nearest milligram onto a glassine
weighing paper. Quantitatively transfer the contents of the paper to a 1 L volumetric flask. Add approximately 800 mL of water.
Add 2 mL of nitric acid into the flask with a pipette. Swirl to dissolve the solids. Fill to the mark with water. The L-cysteine
solution stabilizes the ionic mercury and is used to prepare working standards.
Reagent Chemicals, American Chemical Society Specifications,ACS Reagent Chemicals, Specifications and Procedures for Reagents and Standard-Grade Reference
Materials, 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.
D7623 − 20
9.2 Mercuric Chloride Stock Solution—Weigh 0.0677 g of mercuric chloride onto weighing paper. Quantitatively transfer the
material to a 500 mL volumetric flask using the L-cysteine solution prepared in accordance with 9.1. Fill to the mark with
L-cysteine solution and mix. This results in a mercury concentration of 100 mg ⁄kg.
9.3 Working Standards Set—Prepare a set of mercury standards that are appropriate to the range settings on the instrument in
use. An example of such a set follows.
9.3.1 With a 5 mL pipette, transfer an aliquot of the mercuric chloride stock solution to a 100 mL volumetric flask. Fill the flask
to the mark with L-cysteine solution and mix. This makes a 5 mg ⁄kg standard.
9.3.2 With a 1 mL pipette, transfer an aliquot of the mercuric chloride stock so
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