Overview
ISO 20647:2015 - "Infant formula and adult nutritionals - Determination of total iodine - Inductively coupled plasma mass spectrometry (ICP‑MS)" defines a validated analytical procedure for measuring total iodine in powdered and ready‑to‑feed infant formula and adult nutritional products using ICP‑MS. The standard covers sample preparation, digestion, stabilization, calibration, measurement and data acceptability, and includes interlaboratory precision results (Annex A).
Key technical topics and requirements
- Scope and ranges: Applicable to reconstituted products from 0.5 µg/100 g to 1 500 µg/100 g and to ready‑to‑feed products from 2.5 µg/100 g to 1 000 µg/100 g using ICP‑MS. Interlaboratory test levels reported ranged 3.47 µg/100 g to 124 µg/100 g.
- Principle: Chemical digestion of the sample (potassium hydroxide, KOH) in an oven or open‑vessel microwave system, stabilization of iodine with ammonium hydroxide and sodium thiosulfate, filtration, dilution and direct analysis by inductively coupled plasma mass spectrometry.
- Reagents and materials: Specifies analytical‑grade reagents (KOH, NH4OH, Na2S2O3, nitric and perchloric acids), high‑purity water and recommended reference materials and standards (including NIST SRM 1849a and iodide stock solutions).
- Calibration and QA: Guidance on preparation of intermediate and calibration standards, use of an internal standard (praseodymium), continuing calibration verification (CCV), conditioning and carrier solutions, and acceptance criteria for analytical data.
- Precision and validation: Includes repeatability and reproducibility data from interlaboratory studies (see Annex A) and directs users to procedures for calculating results.
- Safety note: Alerts users to hazardous materials and the responsibility to follow appropriate safety and regulatory limits.
Practical applications
- Routine and regulatory testing of infant formula and adult/pediatric nutritional formula for compliance with labeling and nutritional requirements.
- Quality control in manufacturing plants to monitor iodine fortification and batch consistency.
- Analytical method for contract testing laboratories and food safety/regulatory agencies performing trace mineral analysis.
- Reference method for method validation, interlaboratory studies and proficiency testing involving iodine determination in complex dairy‑based matrices.
Who should use ISO 20647:2015
- Food and dairy quality assurance teams
- Industrial analytical laboratories and contract testing providers
- Regulatory authorities and public health laboratories
- Instrument manufacturers and method developers seeking standardized ICP‑MS protocols for iodine
Related standards and references
- AOAC Official Method 2012.15 - equivalent method for total iodine (as noted in ISO 20647)
- NIST SRM 1849a - recommended reference material for infant/adult nutritional formula
Keywords: ISO 20647, iodine determination, infant formula, adult nutritionals, ICP‑MS, total iodine, KOH digestion, analytical method, food testing, NIST SRM 1849a.