ISO 11723:2004

SLOVENSKI STANDARD
SIST ISO 11723:2005
01-november-2005
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Solid mineral fuels -- Determination of arsenic and selenium -- Eschka's mixture and
hydride generation method
Combustibles minéraux solides -- Dosage de l'arsenic et du sélénium -- Mélange
d'Eschka et méthode par production d'hydrure
Ta slovenski standard je istoveten z: ISO 11723:2004
ICS:
75.160.10 Trda goriva Solid fuels
SIST ISO 11723:2005 en
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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SIST ISO 11723:2005

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SIST ISO 11723:2005
INTERNATIONAL ISO
STANDARD 11723
First edition
2004-11-01
Solid mineral fuels — Determination of
arsenic and selenium — Eschka's mixture
and hydride generation method
Combustibles minéraux solides — Dosage de l'arsenic et du sélénium —
Mélange d'Eschka et méthode par production d'hydrure

Reference number
ISO 11723:2004(E)
©
ISO 2004

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SIST ISO 11723:2005
ISO 11723:2004(E)
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©
ii ISO 2004 – All rights reserved

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SIST ISO 11723:2005
ISO 11723:2004(E)
Contents Page
1 Scope . 1
2 Normative references . 1
3 Principle . 1
4 Reagents . 1
5 Apparatus . 2
6 Preparation of the test sample . 3
7 Procedure . 3
7.1 Blank determination . 3
7.2 Preparation of test solution . 3
7.3 Preparation of calibration standards . 3
7.4 Preparation for measurement . 4
7.4.1 General . 4
7.4.2 Arsenic . 4
7.4.3 Selenium . 4
8 Measurement by atomic absorption or atomic fluorescence spectrometry after hydride
generation . 4
9 Expression of results . 5
10 Precision . 5
10.1 Repeatability . 5
10.2 Reproducibility critical difference . 5
11 Test report . 6
©
ISO 2004 – All rights reserved iii

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SIST ISO 11723:2005
ISO 11723:2004(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.
ISO11723 was prepared by Technical Committee ISO/TC 27, Solid mineral fuels, Subcommittee SC5,
Methods of analysis.
©
iv ISO 2004 – All rights reserved

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SIST ISO 11723:2005
INTERNATIONAL STANDARD ISO 11723:2004(E)
Solid mineral fuels — Determination of arsenic and selenium —
Eschka's mixture and hydride generation method
1Scope
This International Standard specifies a method using Eschka's mixture during ashing, extraction of the ash
residue with acid, and hydride generation atomic absorption spectrometry or hydride generation atomic
fluorescence spectrometry, for the determination of arsenic and selenium in solid mineral fuels.
NOTE The method is also applicable to the determination of the analytes by hydride generation inductively coupled plasma
atomic emission spectrometry.
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 687:2004, Solid mineral fuels — Coke — Determination of moisture in the general analysis test sample
ISO 1170:1977, Coal and coke — Calculation of analyses to different bases
ISO 3696:1987, Water for analytical laboratory use — Specification and test methods
ISO 5068:1983, Brown coals and lignites — Determination of moisture content — Indirect gravimetric method
ISO 5069-2:1983, Brown coals and lignites — Principles of sampling — Part2: Sample preparation for
determination of moisture content and for general analysis
ISO 11722:1999, Solid mineral fuels — Hard coal — Determination of moisture in the general analysis test
sample by drying in nitrogen
ISO 13909-4:2001, Hard coal and coke — Mechanical sampling — Part 4: Coal — Preparation of test samples
ISO 13909-6:2001, Hard coal and coke — Mechanical sampling — Part 6: Coke — Preparation of test samples
3 Principle
A known mass of the sample is ignited in intimate contact with Eschka's mixture in an oxidizing atmosphere at
◦
800 C to remove the organic matter. The residue is then extracted with hydrochloric acid and the analytes
determined by hydride generation atomic absorption spectrometry or hydride generation atomic fluorescence
spectrometry.
4Reagents
WARNING — Care must be exercised when handling reagents, many of which are toxic and corrosive.
During the analysis, unless otherwise stated, use only reagents of recognized analytical reagent grade and
water conforming to Grade 1 of ISO 3696.
©
ISO 2004 – All rights reserved 1

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SIST ISO 11723:2005
ISO 11723:2004(E)
4.1 Eschka's mixture, composed of two parts by mass of light magnesium oxide and one part by mass of
anhydrous sodium carbonate.
ρ 1,19 g/ml
4.2 Hydrochloric acid ().
20
4.3 Nitric acid ()ρ 1,42 g/ml.
20
4.4 Potassium iodide solution, 500 g/l. Dissolve 50 g of analytical reagent (AR) grade KI in distilled water
and adjust the volume to 100 ml (for determination of As).
4.5 Sodium borohydride solution. Weigh 1,50 g of sodium borohydride (NaBH ) and 0,4 g of sodium
4
hydroxide (NaOH) into a plastic bottle of 125 ml capacity and add 100 ml of distilled water. Prepare freshly on
the day of use. Alternatively, commercially available pressed pellets of sodium borohydride may be used.
4.6 Arsenic stock solution (100 mg/l). Dissolve 0,132 0 g± 0,000 5 g of arsenic trioxide (As O of 99,9 %
2 3
◦
purity, dried at 110 C for 1 h) in 25 ml of 20 % KOH solution. Add approximately 50 ml of water and 20 ml of
hydrochloric acid (4.2). Adjust the volume with wat
...