Overview
ISO 14378:2009 (IDF 167:2009) specifies a validated high-performance liquid chromatography (HPLC) method for the determination of iodide content in pasteurized whole milk and dried skimmed milk. The standard covers measurement ranges of 0.03–1 µg/g for pasteurized whole milk and 0.3–10.0 µg/g for dried skimmed milk. The method is intended for the quantitative determination of free (ionic) iodide using reverse‑phase ion‑pair HPLC with electrochemical detection.
Key topics and requirements
- Scope and analyte: Measurement of ionic iodide in milk and milk powder within the stated ranges; note that 5–10% of total iodide can be organically bound in fresh, high‑quality samples.
- Principle: Dilute sample, remove insoluble/high‑molecular‑mass material by filtration through a 25 000 D cut‑off membrane, separate iodide by reverse‑phase ion‑pair HPLC and detect with an electrochemical detector using a silver working electrode (0–+50 mV).
- Reagents and eluent: Analytical/HPLC‑grade reagents including acetonitrile, hexadecyltrimethylammonium chloride (ion‑pair reagent), disodium hydrogen phosphate; eluent is acetonitrile/water (68+32 v/v) with ion‑pairing salt, pH 6.8.
- Standards and calibration: Prepare iodide stock and working standards; build a calibration graph by linear least‑squares (exclude zero); required correlation coefficient ≥ 0.99.
- Apparatus and conditions: Typical HPLC setup-pump (≈2 ml/min), injector (50–200 µl), C‑18 analytical column (e.g., 4.7 × 110 mm, 5 µm), optional guard column, electrochemical detector (d.c. or pulsed amperometric mode). Sample clean‑up uses centrifugation with membrane filter cones or disposable ultrafiltration units.
- Quality and safety notes: Protect iodide solutions from light; follow laboratory safety and ISO water quality (ISO 3696) for analytical use.
Applications and users
ISO 14378:2009 is used for:
- Dairy quality control to monitor iodide levels in milk and milk powder.
- Regulatory and compliance testing where iodine/nutrient levels are regulated or labelled.
- Food safety and nutrition analysis in public health and research programs.
- Method development and validation in analytical chemistry laboratories focused on trace halides.
Typical users:
- Dairy industry laboratories and quality managers
- Accredited food testing and contract laboratories
- Regulatory agencies monitoring iodine in food
- Academic and research laboratories studying micronutrients in dairy
Related standards
- ISO 3696 - Water for analytical laboratory use (required water quality)
- ISO 707 | IDF 50 - Recommended sampling method for milk and milk products (referenced)
Keywords: ISO 14378:2009, iodide determination, HPLC, milk analysis, dried milk, ion‑pair chromatography, electrochemical detector, dairy laboratory, iodine in milk.