Overview
ISO 11723:2016 is an international standard that specifies a precise analytical method for determining arsenic and selenium content in solid mineral fuels. This method combines the use of Eschka’s mixture during ashing with an acid extraction step, followed by quantification through hydride generation atomic absorption spectrometry (AAS) or atomic fluorescence spectrometry (AFS). The standard is essential for ensuring accurate, reproducible measurements of these toxic elements in coal, coke, lignite, and other solid mineral fuels, supporting compliance with environmental and safety regulations.
Key Topics
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Scope and Purpose
Defines a robust procedure for arsenic and selenium determination that applies to various solid mineral fuels. It also includes optional use of inductively coupled plasma atomic emission spectrometry (ICP-AES) equipped with hydride generation.
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Sample Preparation
Emphasizes precise sample handling, including moisture equilibration and preparation of a test portion mixed with Eschka’s mixture. Controlled ashing at 800 °C removes organic matter without loss of analytes.
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Reagents and Standards
Details preparation of essential reagents such as Eschka’s mixture, hydrochloric and nitric acid, potassium iodide, sodium borohydride for hydride generation, and arsenic and selenium stock and working standards. Use of analytical-grade chemicals and Grade 1 pure water is mandatory to ensure accuracy.
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Analytical Procedure
Covers blank determinations, test solution preparation, calibration standard preparation, and preparation of samples for measurement with specific treatments for arsenic and selenium. Includes careful control of temperature and timing to optimize analyte reduction before measurement.
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Measurement Techniques
Implements hydride generation coupled with atomic absorption or atomic fluorescence spectrometry for selective determination of arsenic (at 193.7 nm) and selenium (at 196.0 nm). The standard allows flexibility in instrumentation with guidance to follow manufacturers’ instructions for optimal performance.
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Result Expression and Precision
Specifies calculation methods for reporting results including adjustments for moisture content. Precision criteria such as repeatability and reproducibility are outlined for quality control and validation.
Applications
ISO 11723:2016 provides a vital analytical reference for:
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Environmental Monitoring
Measuring arsenic and selenium in coal and related materials to assess potential environmental contamination during mining, processing, or combustion.
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Fuel Quality Control
Ensuring compliance with regulatory limits for hazardous elements in solid mineral fuels used in power generation or industry.
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Research and Development
Facilitating studies related to trace element behavior in solid fuels, improving fuel processing techniques, and developing cleaner combustion technologies.
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Regulatory Compliance
Assisting laboratories and industries in meeting national and international emission standards by accurately determining arsenic and selenium contents.
Related Standards
ISO 11723:2016 references and complements several other ISO standards critical for solid mineral fuel analysis:
- ISO 5069-2 – Sampling methods and preparation of coal and lignite for analysis.
- ISO 5068-2 – Moisture determination in brown coals and lignites, relevant for correcting results.
- ISO 11722 – Moisture content determination in hard coal samples.
- ISO 687 – Moisture determination in coke samples for accurate compositional data.
- ISO 13909-4 & ISO 13909-6 – Mechanical sampling and preparation of coal and coke test samples.
- ISO 3696 – Quality requirements for laboratory water ensuring chemical purity essential for reagent preparation.
These interconnected standards provide a comprehensive framework for sample preparation, moisture analysis, and overall quality assurance in mineral fuel testing.
Keywords: ISO 11723:2016, arsenic determination, selenium analysis, solid mineral fuels, Eschka’s mixture, hydride generation, atomic absorption spectrometry, atomic fluorescence spectrometry, coal quality control, fuel contamination analysis, analytical chemistry standard, environmental monitoring.