ASTM D4606-21

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Designation: D4606 − 15 D4606 − 21
Standard Test Method for
Determination of Arsenic and Selenium in Coal by the
Hydride Generation/Atomic Absorption Method
This standard is issued under the fixed designation D4606; 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 arsenic in the range of 0.7 ug ⁄g to 12 ug ⁄g and selenium in the range of
0.6 ug ⁄g to 5 ug ⁄g in coal.
1.2 Units—The values stated in SI units are to be regarded as standard. No other units of measurement are included in this The
values given in parentheses after SI units are provided for information only and are not considered standard.
1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility
of the user of this standard to establish appropriate safety safety, health, and healthenvironmental practices and determine the
applicability of regulatory limitations prior to use.
1.4 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:
D346 Practice for Collection and Preparation of Coke Samples for Laboratory Analysis
D2013 Practice for Preparing Coal Samples for Analysis
D3173 Test Method for Moisture in the Analysis Sample of Coal and Coke
D3180 Practice for Calculating Coal and Coke Analyses from As-Determined to Different Bases
D7582 Test Methods for Proximate Analysis of Coal and Coke by Macro Thermogravimetric Analysis
3. Summary of Test Method
3.1 Arsenic and selenium are determined by mixing a weighed coal sample of known mass with Eschka mixture and igniting at
750 °C. The mixture is dissolved in hydrochloric acid and the gaseous hydride of each element is generated from the appropriate
oxidation state and determined by atomic absorption spectrophotometry.
This test method is under the jurisdiction of ASTM Committee D05 on Coal and Coke and is the direct responsibility of Subcommittee D05.29 on Major Elements in
Ash and Trace Elements of Coal.
Current edition approved Nov. 1, 2015Dec. 1, 2021. Published December 2015December 2021. Originally approved in 1986. Last previous edition approved in 20072015
as D4606 – 03D4606 – 15.(2007). DOI: 10.1520/D4606-15.10.1520/D4606-21.
For information concerning experimental work on which this test method is based see: Bosshart, R. E., Price, A. A., and Ford, C. T., “Evaluation of the Effect of Coal
Cleaning on Fugitive Elements, Phase II Final Report, Part II Analytical Methods,” ERDA Report No. C00-44727-35 , 1980, pp. 94–102; Fernandez, F. J., “Atomic Absorption
Determination of Gaseous Hydrides Utilizing Sodium Borohydride Reduction,” Atomic Absorption Newsletter, Vol 12, No. 4, 1973, pp. 93–97; and Brodie, K. G., “A
Comparative Study—Determining Arsenic and Selenium by AAS,” American Laboratory , March 1977, pp. 73–78.
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.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D4606 − 21
4. Significance and Use
4.1 This test method permits measurement of the total mass fraction of arsenic and selenium content of in coal for the purpose
of evaluating these elements where they can be of concern, for example, in coal combustion. When coal samples are prepared for
analysis in accordance with this test method, the arsenic and selenium are quantitatively retained and are representative of the total
amounts mass fraction in the coal.
5. Apparatus
5.1 Atomic Absorption Spectrophotometer, with background correction system and peak profile recording device.
5.2 Hydride Generation Apparatus, for producing the hydrides of arsenic and selenium.
5.3 Burner or Heated Quartz Cell, for thermal decomposition of the hydrides.
5.4 Hotplate, capable of maintaining a temperature of a solution at 60 °C to 90 °C.
5.5 Ignition Crucibles—Porcelain crucible of 30 mL capacity. Do not use a porcelain crucible in which the glaze is flaked.
5.6 Analytical Balance, capable of weighing to a resolution of 0.0001 g.
5.7 Beakers—150 mL and 500 mL.
5.8 Polypropylene Flasks—100 mL and 500 mL also used as a reaction vessel.
6. Reagents
6.1 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.
6.2 Purity of Water—Use high-purity, conductivity water, prepared by passing distilled water (or equivalent) through an ion
exchange resin.
6.3 Eschka Mixture—Prepare (with thorough mixing) a mixture that has a mass fraction of 67 % light calcined magnesium oxide
(MgO) and 33 % anhydrous sodium carbonate (Na CO ). The mixture shall be as free as possible from arsenic and selenium.
2 3
6.4 Hydrochloric Acid Concentrated (sp gr 1.19)—Concentrated hydrochloric acid (HCl).
6.5 Hydrochloric Acid (1 + 4)—Prepare a solution of dilute HCl in water with a volume fraction of 20 % of concentrated
hydrochloric acid (HCl, sp gr 1.19).
6.6 Potassium Iodide Solution 0.2 g ⁄mL—Dissolve 20 g 20 g of potassium iodide (KI) in 100 mL 100 mL of water.
6.7 Sodium Borohydride (Pellets or Solution) Solution 0.03 g ⁄mL—To dilute sodium hydroxide (NaOH) solution (0.01 g ⁄mL), add
sodium borohydride (NaBH ) to give a solution that is 0.03 g ⁄mL sodium borohydride (NaBH ). Prepare fresh daily.
4 4
6.8 Arsenic Stock Solution (1000 mg ⁄L Arsenic)—Certified commercially available standard solution or prepared from primary
standard arsenic trioxide (As O ).
2 3
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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6.9 Selenium Stock Solution (1000 mg ⁄L Selenium)—Certified commercially available standard solution or prepared from
selenium metal (99.99 %).
7. Analysis Sample
7.1 Obtain the sample for coal in accordance with MethodPractice D2013 and the sample for coke in accordance with Practice
D346. Prepare the analysis sample by pulverizing the material to pass a 250 μm (No. 60) 250 μm (No. 60) U.S.A. standard sieve.
7.2 A separate portion of the analysis sample shall be analyzed concurrently for moisture content in accordance with Test Method
D3173 or Test Methods D7582.
7.3 Use certified reference materials, such as the National Institute of Standards and Technology (NIST) Standard Reference
Material (SRM) coals. SRM 1632d and SRM 163a5 are two different coal samples coals (see https://www.nist.gov/srm) that have
certified values for both arsenic and selenium. Results obtained by analyzing these coals for arsenic and selenium using the test
methods described herein can be used for checking analytical technique and test method accuracy. At least one SRM coal sample
should be analyzed as a control when a set of coal samples are analyzed.
8. Sample Preparation and Solution
8.1 To minimize the potential for contamination, clean all labware thoroughly with dilute HCl solution (1 + 9) and rinse with
water. The hydride generation apparatus shall be kept equally clean.
8.2 WeighTransfer approximately 1 g 1 g of coal into a preweighed 30 mL crucible. 30 mL crucible of known mass. Record the
mass to the nearest 0.0001 g. 0.0001 g. Thoroughly mix the sample with 1.5 g 1.5 g of Eschka mixture and cover the mixture with
an additional 1.5 g 1.5 g of Eschka mixture. Place the sample in a cold muffle furnace. Set the temperature control to 500 °C. Heat
the sample for 1 h. 1 h. Increase the furnace temperature to 750 °C. Continue heating at this temperature for 3 h. Remove the
sample and allow it place in desiccator over a desiccant and allow the sample to cool to room temperature.
8.3 Add 20 mL to 30 mL 20 mL to 30 mL of hot water to a 150 mL beaker. Transfer the contents of the crucible from 8.2 to the
beaker. Add 5 mL of concentrated HCl to the crucible. Then slowly and carefully, with the aid of a stirring rod, transfer the HCl
to the beaker. Rinse any remaining material in the crucible into the beaker with water. Add 15 mL concentrated HCl in three 5 mL
portions to the crucible and transfer to the beaker. Swirl the contents until the Eschka has dissolved (Note 1). Allow the solution
to cool to room temperature and transfer it to a 100 mL polypropylene volumetric flask. Dilute to volume with water.
NOTE 1—Some residue can remain.
9. Blank
9.1 Weigh 15 g of Transfer a mass of 15 g of Eschka mixture into a crucible. Heat as described in 8.2. Add 100 mL to 150 mL
hot deionized water to a 500 mL 500 mL beaker. Transfer the contents of the crucible to the beaker. Add 25 mL concentrated HCl
to the crucible. Then slowly and carefully, with the aid of a stirring rod, transfer the HCl to the beaker. Rinse any remaining
material in the crucible into the beaker with water. Add 75 mL concentrated HCl in three 25 mL portions to the crucible and transfer
to the beaker. Swirl the contents until the Eschka has dissolved (Note 1). Allow the solution to cool to room temperature and
transfer to a 500 mL polypropylene volumetric flask. Dilute to volume with water.
10. Procedure for Arsenic
10.1 The solutions and preparations described are typical for North American coals. Different solution mass concentrations can
be required to establish suitable analytical results for those elements with mass fractions outside the typical range. Each analyst
shall determine the sensitivity and optimum method of calibration of their own equipment and choose standards with mass
concentration ranges compatible with the samples and instruments specific to their work. Twenty millilitres is a normal working
volume for batch hydride generation systems. If a hydride generation system is designed to accommodate other than 20 mL 20 mL
(sample + acid), a different volume can be used and all reagents and sample volumes can be ratioed accordingly.
10.2 Prepare an intermediate arsenic standard 1 mL to 10 μgby adding 1 mL of⁄mL from the stock solution. solution in 6.8 to a
D4606 − 21
100 mL volumetric flask and diluting to volume with water. Prepare fresh daily. Prepare a working standard (Note 2) by adding
1 mL of the intermediate standard to a 100 mL polypropylene volumetric flask. Dilute to volume with blank (Section 9).
NOTE 2—Five millilitres of the working standard should produce a signal approximately in the middle of the linear dynamic range for the atomic
absorption operating conditions chosen.
10.3 Prepare three calibration standards by combining volumes of the working standard and blank solution that yield a total
volume equivalent to the analytical volume (Av) (see Annex A1) in a reaction flask. Dilute to 20 mL with HCl (1 + 4).
10.4 Prepare a reagent blank by adding a volume of blank solution equivalent to the analytical volume (Av) (see Annex A1) to
a reaction flask and di
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