ISO 10698:1994

Overview

ISO 10698:1994 - Steel - Determination of antimony content - Electrothermal atomic absorption spectrometric method specifies a quantitative laboratory procedure to determine antimony (Sb) in steel by electrothermal atomic absorption spectrometry (ETAAS). The method covers sample dissolution in hydrochloric and nitric acids, dilution, introduction of aliquots into an electrothermal atomizer, and measurement of the Sb resonance line at 217.6 nm using an antimony lamp with background correction. It is applicable to Sb contents from 0.0005% (m/m) to 0.010% (m/m).

Key topics and technical requirements

• Scope & principle: Dissolve a weighed test portion in HCl and HNO3, dilute to volume, and measure atomic absorption at 217.6 nm in an electrothermal atomizer. Calibration is by the standard additions technique to compensate for matrix effects.
• Analytical range: Applicable for Sb contents between 0.0005% and 0.010% (m/m).
• Detection & sensitivity:
  • Characteristic mass requirement: < 25 pg (instrumental criterion).
  • Limit of detection requirement: less than 20 pg of Sb.
• Reagents & apparatus: Use analytical-grade acids (HCl, HNO3), orthophosphoric acid for special cases, grade-A volumetric glassware, micropipettes (10–500 µL), autosampler, and ETAAS with background correction and an Sb hollow-cathode or electrodeless discharge lamp.
• Sample preparation: Typical test portion masses depend on expected Sb level (e.g., ~1.00 g for 0.0005–0.005% range; ~0.25 g for 0.005–0.010% range). Procedure includes digestion, filtration into volumetric flask, and preparation of blank and spiked (addition) solutions.
• Quality criteria: Instrumental performance and precision evaluated by inter‑laboratory comparison according to ISO 5725; blank acceptability (antimony in blank ≤ 10 ppb); graph linearity and precision checks required.
• Special cases: For steels containing tungsten or niobium, an orthophosphoric acid step and evaporation are specified to avoid interferences.

Applications and users

• Steel and alloy laboratories performing elemental analysis and composition certification.
• Metallurgical quality-control and production labs monitoring trace Sb to meet material specifications.
• Independent testing and inspection bodies providing conformity assessment for steel products.
• Research labs studying trace impurities in ferrous alloys.

Related standards

• ISO 5725 - Precision of test methods (repeatability & reproducibility)
• ISO 377-2 - Sampling of wrought steels for chemical composition
• ISO 3696 - Water for analytical use
• ISO 385-1, ISO 648, ISO 1042 - Laboratory glassware specifications

This standard is essential when accurate, trace-level determination of antimony in steel is required, providing reproducible ETAAS procedures, performance criteria, and sample-handling instructions to ensure reliable results.