Overview
ISO 11433:2020 specifies a molecular absorption spectrophotometric method for the determination of titanium content in nickel alloys using the diantipyrylmethane reagent. The method is applicable for titanium mass fractions from 0.3 % to 5.0 % (with evidence that it can be extended to 0.05 %). It outlines sampling, reagents, apparatus, procedure, calibration and result expression for reproducible spectrophotometric analysis.
Key topics and requirements
- Principle: dissolve alloy in hydrochloric and nitric acids, evaporate with sulphuric acid, form a yellow Ti–diantipyrylmethane complex and measure absorbance at about 390 nm.
- Applicability range: 0.3–5.0 % Ti (note: extension to 0.05 % reported possible).
- Interferences: Molybdenum causes a positive bias (~0.001 % Ti per 1.0 % Mo). The method can be modified to determine titanium in alloys containing tungsten and/or tantalum.
- Reagents & standards: uses analytical-grade acids, diantipyrylmethane reagent, ascorbic and oxalic acids, NaCl, and titanium standard solutions (preparations described).
- Apparatus: class A volumetric glassware (ISO 648 / ISO 1042), spectrophotometer calibrated for 390 nm with 10 mm cells, and routine lab equipment.
- Procedure highlights:
- Test portion mass depends on expected Ti content (e.g., ~0.20 g for 0.3–3.0 %).
- Blank test run in parallel.
- Colour development: add HCl, ascorbic acid, NaCl, then diantipyrylmethane; allow 40 minutes before measurement.
- Calibration curve prepared from 25 mg/L titanium standard (series giving 0–2.5 µg Ti/mL).
- Check test: run known alloy grade in parallel for method performance verification.
- Quality: use grade 2 water (ISO 3696) and class A glassware; follow sampling precautions (remove oil with acetone if needed).
Applications and users
ISO 11433:2020 is intended for:
- Metallurgical and chemical testing laboratories performing titanium assays in nickel-based alloys.
- Quality control in aerospace, power generation, chemical processing and other industries relying on nickel alloys.
- Alloy manufacturers and independent conformity assessment bodies verifying composition for material certification, R&D, and failure analysis.
Keywords: ISO 11433:2020, nickel alloys, titanium determination, diantipyrylmethane, molecular absorption spectrophotometry, spectrophotometric method.
Related standards
- ISO 648 - Laboratory glassware - Single-volume pipettes
- ISO 1042 - Laboratory glassware - One-mark volumetric flasks
- ISO 3696 - Water for analytical laboratory use - Specification and test methods
For implementation, consult the full ISO 11433:2020 text for complete procedural details, safety and performance requirements.
Open preview (PDF)Nickel alloys — Determination of titanium content — Diantipyrylmethane molecular absorption method