ISO 11723:2025

Overview

ISO 11723:2025 defines a standardized laboratory method for the determination of arsenic and selenium in solid mineral fuels (coal and coke). The method combines ashing with Eschka's mixture, acid extraction of the ash residue, and hydride generation coupled to atomic spectrometric detection: hydride generation atomic absorption spectrometry (HG-AAS), hydride generation atomic fluorescence spectrometry (HG-AFS), or hydride generation inductively coupled plasma atomic emission spectrometry (HG‑ICP‑AES).

This procedure is intended for reliable trace-level analysis of these toxic elements in quality control, environmental monitoring and regulatory compliance for the coal and coke sectors.

Key Topics

• Principle: Sample is ignited with Eschka's mixture in an oxidizing atmosphere to remove organics, the residue is dissolved in hydrochloric acid, and arsenic/selenium are determined using hydride generation and atomic spectrometry.
• Sample preparation: Typical test portion ~0.5 g mixed with specified masses of Eschka's mixture; controlled muffle furnace ashing at 800 °C; extraction with HCl and gravimetric dilution to a defined mass or volume.
• Reagents and standards: Use of analytical-grade reagents, defined stock and working standards for arsenic and selenium, freshly prepared sodium borohydride reducing solution and potassium iodide for arsenic measurements.
• Measurement: Instrument optimization is performed per manufacturer guidance. Reported analytical wavelengths in the standard: As at 193.7 nm and Se at 196.0 nm. Hydride generation improves sensitivity and reduces matrix effects for volatile hydride-forming elements.
• Quality controls: Blank determinations are performed concurrently. Calibration standards are prepared in a matrix-matched Eschka blank. Duplicate test portions and method blanks support traceability.

Applications

• Routine laboratory determination of arsenic and selenium in coal and coke for:
  • Environmental monitoring and emissions control
  • Product quality and safety assessment
  • Compliance with regulatory limits and reporting
• Beneficial where low detection limits and reduced spectral interferences are required; hydride generation is particularly effective for volatile species and trace analysis.

Related Standards

• ISO 687 - Moisture determination for coke analysis sample
• ISO 1170, ISO 3696 - Calculation and laboratory water quality requirements
• ISO 13909 series and ISO 18283 - Sampling and preparation of test samples for coal and coke

Practical value: Implementing ISO 11723:2025 ensures a harmonized, reproducible approach to trace arsenic and selenium analysis in solid mineral fuels, facilitating consistent results across laboratories and supporting regulatory and commercial decision-making.