ISO 11723:2016

INTERNATIONAL ISO
STANDARD 11723
Second edition
2016-11-15
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 11723:2016(E)
©
ISO 2016

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ISO 11723:2016(E)

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ii © ISO 2016 – All rights reserved

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ISO 11723:2016(E)

Contents Page
Foreword .iv
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Principle . 1
5 Reagents . 2
6 Apparatus . 3
7 Preparation of the test sample . 3
8 Procedure. 3
8.1 Blank determination . 3
8.2 Preparation of test solution . 3
8.3 Preparation of calibration standards . 4
8.4 Preparation for measurement . 4
8.4.1 General. 4
8.4.2 Arsenic . 4
8.4.3 Selenium . . 4
9 Measurement by atomic absorption or atomic fluorescence spectrometry after
hydride generation . 4
10 Expression of results . 5
11 Precision . 5
11.1 Repeatability . 5
11.2 Reproducibility critical difference . 6
12 Test report . 6
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ISO 11723:2016(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
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electrotechnical standardization.
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described in the ISO/IEC Directives, Part 1. In particular the different approval criteria needed for the
different types of ISO documents should be noted. This document was drafted in accordance with the
editorial rules of the ISO/IEC Directives, Part 2 (see www.iso.org/directives).
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Technical Barriers to Trade (TBT) see the following URL: www.iso.org/iso/foreword.html.
The committee responsible for this document is ISO/TC 27, Solid minerals fuels, Subcommittee SC 5,
Methods of analysis.
This second edition cancels and replaces the first edition (ISO 11723:2004), which has been technically
revised. This document incorporates changes related to dated references and other minor items
following its systematic review.
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INTERNATIONAL STANDARD ISO 11723:2016(E)
Solid mineral fuels — Determination of arsenic and
selenium — Eschka’s mixture and hydride generation
method
1 Scope
This document 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 documents are referred to in the text in such a way that some or all of their content
constitutes requirements 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, Solid mineral fuels — Coke — Determination of moisture in the general analysis test sample
ISO 1170, Coal and coke — Calculation of analyses to different bases
ISO 3696, Water for analytical laboratory use — Specification and test methods
ISO 5068-2, Brown coals and lignites — Determination of moisture content — Part 2: Indirect gravimetric
method for moisture in the analysis sample
ISO 5069-2, Brown coals and lignites — Principles of sampling — Part 2: Sample preparation for
determination of moisture content and for general analysis
ISO 11722, Solid mineral fuels — Hard coal — Determination of moisture in the general analysis test
sample by drying in nitrogen
ISO 13909-4, Hard coal and coke — Mechanical sampling — Part 4: Coal — Preparation of test samples
ISO 13909-6, Hard coal and coke — Mechanical sampling — Part 6: Coke — Preparation of test samples
3 Terms and definitions
No terms and definitions are listed in this document.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— IEC Electropedia: available at http://www.electropedia.org/
— ISO Online browsing platform: available at http://www.iso.org/obp
4 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.
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ISO 11723:2016(E)

5 Reagents
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.
5.1 Eschka’s mixture, composed of two parts by mass of light magnesium oxide and one part by mass
of anhydrous sodium carbonate.
5.2 Hydrochloric acid (ρ 1,19 g/ml).
20
5.3 Nitric acid (ρ 1,42 g/ml).
20
5.4 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).
5.5 Sodium borohydride solution. Weigh 1,50 g of sodium borohydride (NaBH ) and 0,4 g of sodium
4
hydroxide (N
...