Overview
ISO 10697-2:1994 specifies a laboratory method for the determination of total calcium content in steel by flame atomic absorption spectrometry (FAAS). The method covers sample preparation, fusion of acid‑insoluble residue, use of a spectrochemical buffer, instrumentation settings and calibration. It is applicable to calcium concentrations between 0.0005 % (m/m) and 0.005 % (m/m).
Key topics and technical requirements
- Principle: dissolve test portion in hydrochloric and nitric acids; fuse the acid‑insoluble residue with sodium carbonate; add potassium chloride/lanthanum nitrate solution as a spectrochemical buffer; aspirate into a dinitrogen monoxide–acetylene flame; measure atomic absorption at 422.7 nm using a calcium hollow‑cathode lamp.
- Calibration & performance:
- Calibration graph prepared for each series; linearity and precision criteria specified (e.g., standard deviation limits for calibration absorbances).
- Limit of detection in a matrix similar to the final test solution: better than 0.02 μg Ca per mL.
- Characteristic concentration requirement: better than 0.05 μg Ca per mL.
- Sample preparation & apparatus:
- Use class A volumetric glassware, low‑calcium reagents and Grade 2 water (ISO 3696).
- Filtration (0.22 μm), platinum crucible fusion, muffle furnace (500–800 °C) and careful handling of perchloric and hydrofluoric acids are described.
- Atomic absorption spectrometer must be equipped for a stable, fuel‑lean N2O–acetylene flame and meet instrument precision requirements.
- Safety: cautions about perchloric acid vapors and acetylene handling are included; glassware contamination checks recommended.
Applications
- Routine and quality‑control analysis of total calcium in steel and ferrous alloys where trace calcium affects properties (casting, inclusion control, alloy specification).
- Verification of alloy composition for compliance with material specifications and acceptance testing.
- Method selection when precise low‑level calcium quantification (0.0005–0.005 % m/m) is required.
Who uses this standard
- Metallurgical and materials testing laboratories
- Steel producers and foundries performing chemical analysis and process control
- Third‑party inspection and certification bodies
- Instrument and reagent suppliers designing FAAS methods for steel matrices
Related standards
- ISO 10697‑1 - Determination of acid‑soluble calcium content (companion part)
- ISO 3696 - Water for analytical laboratory use
- ISO 5725 - Precision of test methods (repeatability and reproducibility)
- ISO 377‑2 - Sampling and sample preparation for chemical composition of wrought steels
This ISO method provides a validated FAAS procedure for accurate, low‑level determination of total calcium in steel, supporting quality control and compliance in metallurgical analysis.
Open preview (PDF)Steel — Determination of calcium content by flame atomic absorption spectrometry — Part 2: Determination of total calcium content