ISO 23380:2008
(Main)Selection of methods for the determination of trace elements in coal
Selection of methods for the determination of trace elements in coal
ISO 23380:2008 provides guidance on the selection of methods used for the determination of trace elements in coal and coal ash. The trace elements of environmental interest include arsenic, beryllium, boron, cadmium, chlorine, chromium, cobalt, copper, fluorine, lead, manganese, mercury, molybdenum, nickel, selenium, vanadium and zinc. To this list can be added the radioactive trace elements, thorium and uranium. ISO 23380:2008 does not prescribe the methods used for the determination of individual trace elements. The analysis of appropriate CRMs is essential to confirm the accuracy of any method used.
Sélection des méthodes de détermination des éléments en traces dans le charbon
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Standards Content (Sample)
INTERNATIONAL ISO
STANDARD 23380
First edition
2008-10-15
Selection of methods for the
determination of trace elements in coal
Sélection des méthodes de détermination des éléments en traces dans
le charbon
Reference number
ISO 23380:2008(E)
©
ISO 2008
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ISO 23380:2008(E)
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ISO 23380:2008(E)
Contents Page
Foreword. iv
Introduction . v
1 Scope . 1
2 Normative references . 1
3 Definitions . 1
4 Abbreviations . 1
5 Discussion of methods . 2
6 Use of certified reference materials. 4
7 Calculation of results . 4
8 Sensitivity . 5
9 Reporting of results. 6
10 Precision. 6
11 Test report . 6
Annex A (informative) Scheme of analysis for trace elements. 7
Annex B (informative) Alternative dissolution procedures for coal . 8
Bibliography . 9
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ISO 23380:2008(E)
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies
(ISO member bodies). The work of preparing International Standards is normally carried out through ISO
technical committees. Each member body interested in a subject for which a technical committee has been
established has the right to be represented on that committee. International organizations, governmental and
non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the
International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.
International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2.
The main task of technical committees is to prepare International Standards. Draft International Standards
adopted by the technical committees are circulated to the member bodies for voting. Publication as an
International Standard requires approval by at least 75 % of the member bodies casting a vote.
Attention is drawn to the possibility that some of the elements of this document may be the subject of patent
rights. ISO shall not be held responsible for identifying any or all such patent rights.
ISO 23380 was prepared by Technical Committee ISO/TC 27, Solid mineral fuels, Subcommittee SC 5,
Methods of analysis.
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ISO 23380:2008(E)
Introduction
The determination of trace elements in coal and coke is becoming more important due to the considerable
emphasis being placed on the effect of these elements on the environment. In order to have accurate and
precise results for the analysis of trace elements, it is imperative that standard methods be available and that
these methods be based on reliable procedures.
The objective of this International Standard is to assist in the selection of the appropriate methods available to
determine the common trace elements in coal.
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INTERNATIONAL STANDARD ISO 23380:2008(E)
Selection of methods for the determination of trace elements
in coal
1 Scope
This International Standard provides guidance on the selection of methods used for the determination of trace
elements in coal. The trace elements of environmental interest include antimony arsenic, beryllium, boron,
cadmium, chlorine, chromium, cobalt, copper, fluorine, lead, manganese, mercury, molybdenum, nickel,
selenium, thallium, vanadium and zinc. To this list can be added the radioactive trace elements, thorium and
uranium.
This International Standard does not prescribe the methods used for the determination of individual trace
elements. The analysis of appropriate CRMs is essential to confirm the accuracy of any method used (see
ISO Guide 33).
2 Normative references
The following referenced documents are indispensable for the application of this document. For dated
references, only the edition cited applies. For undated references, the latest edition of the referenced
document (including any amendments) applies.
ISO 1213-2, Solid mineral fuels — Vocabulary — Part 2: Terms relating to sampling, testing and analysis
ISO 5725 (all parts), Accuracy (trueness and precision) of measurement methods and results
ISO Guide 33, Uses of certified reference materials
3 Definitions
For the purpose of this document, the definitions given in ISO 1213-2 apply.
4 Abbreviations
AAS atomic absorption spectrometry
AFS atomic fluorescence spectrometry
CVAAS cold-vapour atomic absorption spectrometry
GFAAS graphite-furnace atomic absorption spectrometry
IC ion chromatography
ICP-AES inductively coupled plasma atomic emission spectrometry—often referred to as ICP-OES, i.e.
inductively coupled plasma optical emission spectrometry
ICP-MS inductively coupled plasma mass spectrometry
INAA instrumental neutron activation analysis
ISE ion selective electrode
XRF X-ray fluorescence spectrometry
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ISO 23380:2008(E)
5 Discussion of methods
5.1 General
A summary of techniques applicable to the determination of each of the trace elements are discussed below.
A schematic of procedures used for trace element determinations is given in Annex A.
It is critical that moisture be determined on the sample to enable calculation to bases other than “air-dried”.
NOTE 1 There are digestion procedures applicable to unashed coal. The application of these is discussed in Annex B.
NOTE 2 Boron, chlorine, fluorine, mercury and selenium are released if coal is ashed; thus, it is not possible to
estimate the concentration of these elements in coal by analysing a laboratory-prepared ash.
Where digestion procedures require ashing of the coal, it is critical to determine the ash yield to enable
calculation of trace elements content in the coal sample; see Clause 7. Ashing procedures are described in
[6]
ISO 15238 . Coals are ashed in silica or quartz dishes, or in platinum or platinum alloy crucibles/basins, in a
conventional ashing furnace. The furnace temperature is ramped from ambient to a maximum of 500 °C over
1 h to 3 h and held at this temperature until the carbonaceous material is completely oxidized or for a
maximum of 18 h. The ramp rate is selected to avoid ignition and mechanical loss of sample.
5.2 Arsenic and selenium
Arsenic and selenium are determined by hydride generation/atomic absorption or atomic fluorescence
techniques following the ashing of the coal at 800 °C in the presence of Eschka mixture and dissolution with
[3]
hydrochloric acid. ISO 11723 is the recommended method for the determination of arsenic and selenium in
coal.
Arsenic can be determined in coal by the analysis of ash prepared in a laboratory at a temperature no greater
than 500 °C. Selenium is vaporized at quite low temperatures and is not recovered in ash. There is no
International Standard for the determination of arsenic in coal ash. A suitable procedure is the dissolution of
the ash either by lithium metaborate/tetraborate fusion or by mixed acids (nitric, hydrochloric and hydrofluoric
acids) and determination of the analyte by hydride/AAS or hydride/AFS. This element can also be determined
by ICP-MS if the interference caused by argon chloride is eliminated.
5.3 Boron
Boron is determined by ICP-AES following the ashing of the coal at 800 °C in the presence of Eschka mixture
[7]
and dissolution with hydrochloric acid; see AS 1038.10.3 . This dissolution procedure is the same as that
[3]
used for arsenic and selenium. The procedure is set out in ISO 11723 .
5.4 Antimony, beryllium, cadmium, chromium, cobalt, copper, lead, manganese,
molybdenum, nickel, thallium, vanadium, zinc, thorium and uranium
5.4.1 General
Antimony, beryllium, cadmium, chromium, cobalt, copper, lead, manganese, molybdenum, nickel, thallium,
vanadium, zinc, thorium and uranium are determined by various spectrometric techniques (see
[10]
ASTM D6357 ).
NOTE 1 A number of these trace elements can be determined by XRF; however, in general, the sensitivity is too low to
accurately determine beryllium, cadmium, thallium, thorium and uranium by XRF.
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ISO 23380:2008(E)
Recommended procedures are summarized below.
a) The coal sample is ashed at a maximum temperature of 500 °C to remove the carbonaceous matter.
b) The laboratory-prepared ash is dissolved either by fusion with a mixture of lithium metaborate and
[8]
tetraborate (see AS 1038.14.1 ) or by mixed acids (nitric, hydrochloric and hydrofluoric acids). These
dissolution procedures are applicable to the analysis of coal ash. Note that thorium and uranium can form
insoluble fluorides and precautions shall be taken to prevent this in the presence of hydrofluoric acid.
Thorium and uranium can be determined within 2 h of the preparation of a mixed acid solution of the coal
ash or the fluoride can be removed by evaporation.
The solution obtained by dissolution procedures in which fluoride is complexed with boric acid, can be
used for the determination of trace elements by ICP-AES and ICP-MS.
c) The concentrations of the analytes in solution are determined by spectrometric techniques. Traditionally,
...
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