Overview
ISO 7523:1985 specifies an electrothermal atomic absorption spectrometric (ETAAS) method for determining trace amounts of silver, arsenic, bismuth, cadmium, lead, antimony, selenium, tin, tellurium and thallium in high‑purity, refined, wrought and cast nickel. The method covers independent determination of any one or more of these elements within the concentration ranges given in the standard and uses matched‑matrix calibration and instrumental background correction. Annex A gives an alternative preparation of nickel nitrate matrix solution and Annex B reports interlaboratory test statistics.
Key topics and technical requirements
- Scope: Trace analysis of Ag, As, Bi, Cd, Pb, Sb, Se, Sn, Te and Tl in nickel (specified µg/g ranges per element).
- Principle: Dissolve test portion in nitric acid, dilute to known volume, introduce aliquot into a graphite electrothermal atomizer and measure absorption of resonance lines against calibration solutions in a matched nickel matrix.
- Sample preparation: Typical test‑portion dissolution (example in standard: ~0.9–1.1 g sample, with water and nitric acid, heat, dilute to 100 ml) and preparation of nickel nitrate stock solution to produce 10 g Ni/L matrix for calibration.
- Calibration: Two calibration sets (A for As, Bi, Pb, Sb, Se, Sn, Te, Tl; B for Ag and Cd) using mixed analyte standard solutions and matched nickel matrix. Zero members serve as blank tests when same nitric acid batch is used.
- Instrumentation: ETAAS with background correction (essential), single‑element hollow cathode or electrodeless discharge lamps; recommended atomization temperatures for nickel matrix ~2 600–2 700 °C.
- Quality and precision: Method tested in an interlaboratory program (11 labs) with precision evaluated following ISO 5725; Annex B contains statistical results.
- Interferences and precautions: Attention to contamination (glassware cleaning, chloride avoidance for Ag and Sn), matrix matching to minimize background absorption, and accounting for residual analyte in nickel used for standards.
Applications and users
- Practical applications: Quality control and certification of high‑purity nickel, process monitoring in nickel refining, acceptance testing for wrought and cast nickel products, and trace‑level impurity analysis for research and regulatory compliance.
- Who uses it: Metallurgical and materials testing laboratories, analytical chemists, nickel producers and refiners, QA/QC teams, and regulatory laboratories requiring ETAAS trace‑element methods.
Related standards
- ISO 5725 (precision of test methods - repeatability/reproducibility)
- ISO 1042, ISO 648, ISO 38511 (laboratory glassware and apparatus references)
- ISO 6283 (for specific nickel compositions referenced in the standard)
Keywords: ISO 7523:1985, nickel analysis, electrothermal atomic absorption spectrometry, ETAAS, trace elements, nickel purity, calibration, graphite furnace, sample preparation.