ISO 5189:2023

Overview

ISO 5189:2023 specifies standardized chemical analysis methods for metal impurities in silicon dioxide (SiO2) powders used as raw materials for fine ceramics (advanced/technical ceramics). The standard defines sample preparation, acid decomposition, ICP-OES measurement and calculation/reporting procedures to determine Al, Cd, Ca, Cu, Fe, Pb, Li, Mg, Mn, Ni, K, Na, Ti, Zn and Zr in silica powders. Typical reporting is in mg/kg (dry basis) over the range 1.0–100 mg/kg using inductively coupled plasma–optical emission spectrometry (ICP‑OES).

Key topics and technical requirements

• Analytes & ranges: 15 metal impurity elements, each with a working range of 1.0 mg/kg to 100 mg/kg.
• Sample preparation: Follow ISO 8656‑1 sampling; dry 10 g at 110 °C ± 5 °C for 2 h; weigh 1.0 g ±0.1 mg test portion.
• Acid decomposition: Use analytical‑grade reagents. Typical decomposition: 15 mL HF + 3 mL HNO3, heat to dryness, then dissolve residue with HCl solution for Al/Fe/Ti/Mn or HNO3 solution for other elements; make up to 10 mL volumetric flask to produce the sample solution. Blank decomposition must be run in parallel.
• Reagents & instrumentation: HF, HNO3, HCl (and diluted mixtures), high‑purity water per ISO 3696, and ICP‑OES for element determination.
• Calibration & measurement: Prepare mixed standard (each element 5 mg/L) and calibration series (1, 5, 10, 15, 20 mL to 100 mL) using appropriate acid matrix. Choose ICP‑OES wavelengths free of spectral overlap (standard examples provided in ISO 5189:2023).
• Calculation & reporting: Compute element content from calibration curves and blank-corrected concentrations using the standard formula. Report values to two significant figures in mg/kg (dry). Repeat measurements and follow specified tolerance rules (5 mg/kg tolerance for amounts <50 mg/kg; 25 mg/kg for ≥50 mg/kg).

Practical applications

• Quality control of silicon dioxide raw materials for advanced ceramics, optics, electronics and high‑purity ceramic components
• Incoming raw material inspection for ceramic manufacturers and suppliers to ensure impurity limits that affect mechanical, thermal and electrical properties
• Laboratory method standardization for interlaboratory comparability when using ICP‑OES to quantify silica powder impurities

Who should use this standard

• Analytical and quality control laboratories performing silica impurity testing
• Manufacturers of fine/advanced ceramics and suppliers of SiO2 powders
• Materials engineers and R&D teams concerned with impurity-driven performance issues
• Regulatory and conformity assessment bodies evaluating material specifications

Related standards

• ISO 3696 - Water for analytical laboratory use
• ISO 8656‑1 - Sampling of refractory raw materials and unshaped products

Keywords: ISO 5189:2023, fine ceramics, silicon dioxide powders, ICP‑OES, metal impurities, chemical analysis, acid decomposition, silica powder impurities.