ISO 11400:2021

Overview

ISO 11400:2021 specifies a phosphovanadomolybdate spectrophotometric method for the determination of phosphorus content in nickel, ferronickels and nickel alloys. The method covers quantitative analysis in the range 0.0005 % to 0.05 % (by mass). It describes sample preparation, chemical treatments, extraction, and spectrophotometric measurement to reliably report low-level phosphorus in nickel-based materials.

Keywords: ISO 11400:2021, phosphorus determination, nickel alloys, phosphovanadomolybdate spectrophotometric method, spectrophotometry, metallurgical testing.

Key topics and technical requirements

• Scope and detection range: 0.0005 %–0.05 % P (by mass).
• Sample types and preparation: laboratory samples normally in the form of millings or drillings; clean with high-purity acetone if contaminated by oil or grease; riffling for inhomogeneous particle sizes.
• Chemical digestion and reagents:
  • Dissolution in nitric and hydrochloric acids, followed by fuming with perchloric acid in PFA or PTFE beakers.
  • Use of hydrofluoric acid to complex silicon and refractory elements.
  • Conversion of phosphorus to phosphovanadomolybdic acid (using ammonium metavanadate and hexaammonium heptamolybdate).
  • Addition of citric acid to complex arsenic and extraction of the coloured complex into 4‑methyl‑2‑pentanone (methyl isobutyl ketone).
• Interferences and mitigation:
  • Elements causing interference: arsenic, chromium, hafnium, niobium, silicon, tantalum, titanium and tungsten.
  • Chromium is removed by volatilization as chromyl chloride; other interferences are addressed by complexation (e.g., HF, citric acid).
  • Lowest detection limit achievable only in samples with low levels of interfering elements.
• Measurement and instrumentation:
  • Spectrophotometric measurement at around 355 nm using class A volumetric glassware.
  • Calibration curve establishment, blank tests, and check tests are specified to ensure accuracy.
• Safety considerations: explicit warnings for the use of hydrofluoric acid and perchloric acid; appropriate fume hoods and emergency measures required.

Applications and users

• Routine quality control and acceptance testing by nickel producers, ferronickel manufacturers, and alloy fabricators.
• Analytical and metallurgical laboratories performing trace phosphorus analysis in base metals and nickel alloys.
• Research and development teams assessing impurity levels that affect corrosion resistance, mechanical properties, or processing behavior.
• Regulatory or certification bodies requiring standardized methods for compositional verification.

Related standards

• ISO 648 - Laboratory glassware - Single‑volume pipettes
• ISO 1042 - Laboratory glassware - One‑mark volumetric flasks
• ISO 3696 - Water for analytical laboratory use

ISO 11400:2021 provides a validated, reproducible laboratory procedure for low‑level phosphorus analysis in nickel materials - essential for metallurgical quality assurance, product specification compliance, and process control.