ISO 6101-3:2022

Overview

ISO 6101-3:2022 specifies an atomic absorption spectrometric (AAS) method for the determination of copper content in rubber. The procedure applies to raw rubber, latex and rubber products with copper contents typically above 1 ppm, although lower concentrations can be measured by increasing sample mass, adjusting solution concentrations, or using the standard additions technique to lower detection limits. The standard is the fourth edition (2022) and updates analytical details such as ashing temperatures and acid concentrations to improve accuracy and instrument maintenance.

Key topics and technical requirements

• Principle: Ashing of a representative test portion, dissolution of the inorganic residue, and measurement by AAS at 324.7 nm using a copper hollow‑cathode lamp. An electrothermal (graphite furnace) alternative is permitted.
• Sample preparation:
  • Typical test portions: 1–5 g for rubber products; 5–10 g for raw rubber (milled or finely cut); latex handled per ISO 124.
  • Ashing temperatures: (550 ± 25) °C for raw natural rubber and (950 ± 25) °C for products with high carbon black content (per ISO 247‑1).
  • If ash is black, moisten and re-ash after acid treatment to remove residual carbon.
• Reagents and solutions:
  • Use analytical-grade reagents and high-purity water.
  • Dilute hydrochloric acid (≈2 %) and dilute nitric acid (≈1.6 %) are specified for dissolution; sulfuric and hydrofluoric acids volatilize silicates if required.
  • Preparation of copper standards (stock and working solutions) is described for calibration.
• Instrumentation and operation:
  • AAS with an acetylene/air burner (specified gas pressures) or graphite furnace as alternative.
  • Calibration by external standard graph; standard additions method included (Annex A) to improve low-level quantification.
• Quality and reporting:
  • Blank determinations, number of replicates, expression of results, and precision data are provided (including informative Annex B).

Applications and users

ISO 6101-3:2022 is intended for:

• Rubber manufacturers for incoming material control and product quality assurance.
• Independent testing laboratories performing elemental analysis of rubbers and elastomers.
• R&D and materials scientists investigating metal contamination effects on properties.
• Regulatory and environmental compliance testing where copper content in rubber products must be demonstrated.

Practical uses include troubleshooting contamination sources, verifying raw-material purity, and ensuring compliance with material specifications in automotive, industrial and consumer rubber products.

Related standards

Relevant cross‑references and companion documents:

• ISO 6101 series (other parts covering different metals)
• ISO 247‑1 (ash determination - combustion method)
• ISO 1795 (raw rubber sampling and preparation)
• ISO 123, ISO 124 (latex sampling and solids determination)
• ISO 1042, ISO 648, ISO 835, ISO 1772 (laboratory glassware and crucibles)

Keywords: ISO 6101-3:2022, rubber copper determination, atomic absorption spectrometry, AAS, copper in rubber, rubber testing, ashing, standard additions method.