ASTM D7622-20

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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: D7622 − 10 (Reapproved 2015) D7622 − 20
Standard Test Method for
Total Mercury in Crude Oil Using Combustion and Direct
Cold Vapor Atomic Absorption Method with Zeeman
Background Correction
This standard is issued under the fixed designation D7622; 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 procedure to determine the total mercury content in a sample of crude oil. This test method can
be used for total mercury determination in natural and processed liquid and oil products (gasoline, naphtha, etc.).
1.2 This test method may be applied to samples containing between 5.0 ng ⁄mL to 350 ng ⁄mL of mercury. The results may be
converted to mass basis.
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
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
ε1
D7622 – 10 (2015). . DOI: 10.1520/D7622-10R15.10.1520/D7622-20.
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 service@astm.org. 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
D7622 − 20
D7482 Practice for Sampling, Storage, and Handling of Hydrocarbons for Mercury Analysis
D7623 Test Method for Total Mercury in Crude Oil Using Combustion-Gold Amalgamation and Cold Vapor Atomic Absorption
Method
3. Terminology
3.1 For definitions of terms used in this test method, refer to Terminology D4175.
4. Summary of Test Method
4.1 Controlled heating following thermal decomposition of the analysis sample in air is used to liberate mercury. The sample
is placed into the sample boat, which is inserted in the first chamber of the atomizer, where the sample is heated at controlled
temperature at 300 °C to 500 °C (depending on the selected operation mode). The mercury compounds are evaporated and partially
dissociated forming elemental mercury vapor. Mercury and all decomposition products are carried to the second chamber of the
atomizer heated to about 700 °C to 750 °C (mercury reduction takes place on the surface of heating NiCr coil, thus no catalyst is
required). Mercury compounds are totally dissociated, and the organic matrix of the sample is burnt out. Continuously flowing air
carries mercury and other combustion products through absorbance analytical cell heated up to 750 °C positioned in the light path
of double-wave cold vapor Zeeman atomic absorption spectrophotometer. The mercury resonance line 253.65 nm is split to several
components, one of those falling within the mercury absorbance line (analytical line) profile and another one lying outside
(reference line). Difference between the intensities of these compounds is proportional to number of mercury atoms in the
analytical cell. Absorbance peak area or peak height is a function of the mercury concentration.
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 General configuration of the instrument shall have the following functional components: temperature controlled sample
heating and decomposition furnace, measuring cuvettes, mercury lamp placed in strong magnetic field, polarization modulator to
separate analytical and reference lines, and detector. The following requirements are specified for all approved instruments.
NOTE 2—The 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 Zeeman Mercury Spectrometer—Atomic absorption spectrometer with Zeeman background correction, operating with the
mercury resonance absorption wavelength of 253.7 nm.
6.1.2 The atomizer 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 600 °C.
6.1.3 The heated analytical cell shall be capable to prevent mercury loses due to deposition to cold parts and to prevent mercury
recombination with chlorine. The suggested operating temperature of the analytical cell is at least 700 °C.
6.1.4 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 Boats, quartz, stainless steel, porcelain, or other material as recommended and convenient size suitable for use in
the instrument being used.
6.4 Micropipetters, one or more units of variable volume to cover a range from 10 μL to 250 μL, NIST traceable. Appropriately
sized tips should also be available.
6.5 Ultrasonic Homogenizer—A bath-type ultrasonic homogenizer is used to dissociate particulate mercury and thoroughly mix
the sample.
6.6 Glassware, volumetric flasks of various capacities and Class A 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.
The sole source of supply of the apparatus known to the committee at this time is Lumex model RA 195 available from Ohio Lumex Company, 9263 Ravenna Road,
Unit A-3, Twinsburg, OH 44087. 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.
D7622 − 20
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 of the bulk container is obtained.
7.2 To prevent loss of mercury during storage and handling of samples, follow Practice D7482. Samples 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.
8. Reagents and Materials
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 A standard sample of mercury ions solution (concentration C = 1.0 g ⁄L).
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).
8.5 Nitric Acid, concentrated, Trace Metal Grade or better.
8.6 Combustion Reagents, activated charcoal, 30 × 50 mesh.
8.7 Potassium Dichromate Solution, 4 % (mass)—Place a 4 g portion of potassium dichromate in a volumetric flask (volume
of 100 mL), dissolve in distilled water and dilute with the distilled water up to the mark. The solution is to be stored in a reservoir
made of dark glass with a plug stopper. Storage time is 3 months.
8.8 Dilution Solution—Place 500 mL to 600 mL of distilled water in a heat-resistant glass and pour in carefully 50 mL of
concentrated nitric acid (d = 1.37 g/mL). Stir constantly while pouring in the acid. Transfer to a volumetric flask of 1000 mL
volume, add 5 mL of 4 % potassium dichromate solution and add up with distilled water up to the mark. The solution is to be stored
in a reservoir made of dark glass with a plug stopper. Storage time is 3 months.
8.9 All CRMs, reference crude oils, or calibrating agents shall 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.
9. Preparation of Standards
9.1 Working Standard Set—Prepare a set of standards that are appropriate to the range settings on the instrument in use. An
example of such a set follows:
9.1.1 Place 30 mL of a dilution solution in a volumetric flask (100 mL volume). Then place 2 mL of a standard sample of
mercury ions NIST or other standard reference material issuing bodies’ traceable standard solution (concentration C = 1.0 g ⁄L).
Bring the contents of the volumetric flask up to the mark with the dilution solution and stir thoroughly. This results in a mercury
concentration of 20 mg ⁄L (C ). The solution may be stored in a refrigerator during 6 months.
9.1.2 Place 30 mL of a dilution solution in a volumetric flask (100 mL volume). Then place 10 mL of a standard sample of
mercury solution C = 20 mg ⁄L. Bring the contents of the retort up to the mark with the dilutio
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