ISO 14720-2:2013

Overview

ISO 14720-2:2013 specifies a laboratory method for the determination of sulfur in powders and granules of non-oxidic ceramic raw and basic materials. The standard covers materials that are completely oxidized at high temperature in an oxygen atmosphere (for example carbon and graphite materials) and defines the procedure of burning samples in an oxygen flow followed by analysis of the absorbed sulfur oxides using ICP/OES (inductively coupled plasma optical emission spectrometry) or ion chromatography (IC).

Key scope limits:

• Applicable for sulfur mass fractions ≤ 10% and ash < 20%
• Not suitable for high barium content (barium sulfate-bound sulfur not detectable if Ba ≥ ~10 mg/kg)
• Recommended lower detection limits: 0.5 mg/kg (ICP/OES) and 5 mg/kg (IC)

Key Topics and Requirements

• Principle: Dried sample is combusted at (1 100 ± 20) °C in flowing oxygen; resulting SOx are absorbed in a NaOH/H2O2 solution. The absorption solution (and dissolved ash when applicable) is analysed as sulfate by ICP/OES (ISO 11885) or IC (ISO 10304-1).
• Apparatus & reagents: Combustion device, unglazed porcelain boats, gas-washing bottles, 0.45 µm filtration, ICP/OES (wavelengths for S: 180.731 nm, 182.034 nm), ion chromatograph with anion column and conductivity detector. Oxygen purity ≥ 99.998% and oxygen flow ≈ (20 ± 10) L/h.
• Sample preparation: Representative sampling (e.g., ISO 8656-1), particle size ≤ 160 µm, drying at (110 ± 5) °C to constant mass, contamination avoidance.
• Calibration & performance: Use certified sulfate standard stock solutions and matrix-appropriate calibration; blank determination, standard addition or matrix matching may be required to address matrix effects.
• Interferences: Spectral and physical interferences for ICP/OES (background, overlapping lines, plasma/transport effects); anion cross-interferences for IC (chloride, nitrate, etc.) - separation and suppression techniques recommended.
• Quality and validation: Sections on precision (repeatability, reproducibility), examples of operating parameters, round-robin results, and guidance on uncertainty; informative annexes include combustion device examples and recommended instrument parameters.

Applications and Users

ISO 14720-2 is intended for:

• Refractory and ceramic raw-material laboratories performing sulfur analysis in powders and granules
• Quality control and incoming inspection for ceramic, carbon and graphite feedstocks
• R&D and materials characterization teams needing reliable sulfur quantification
• Certification labs and regulatory bodies requiring standardized sulfur testing methods

Practical benefits include traceable sulfur results, options to choose ICP/OES for lower detection limits or IC for anionic separation, and a documented workflow for sample combustion and absorption.

Related Standards

• ISO 14720-1 - Determination of sulfur: infrared methods
• ISO 11885 - ICP-OES for selected elements
• ISO 10304-1 - IC for dissolved anions (including sulfate)
• ISO 8656-1 - Sampling guidance for powders/granules

Keywords: ISO 14720-2:2013, sulfur determination, ICP/OES, ion chromatography, combustion in oxygen flow, ceramic raw materials, refractory testing, sample preparation, detection limit.