ISO 23305:2020

Overview

ISO 23305:2020 specifies a validated analytical method for the quantitative determination of total biotin (and biocytin) in fortified milk powders, infant formula and adult nutritionals. The method covers both solid (powders) and liquid forms (ready‑to‑feed liquids and concentrates) and uses liquid chromatography (HPLC) coupled with immunoaffinity column clean‑up extraction. Precision data from an interlaboratory study is provided (Annex B) and a method comparison with EN 15607 is given (Annex C). The method is equivalent to AOAC Official Method 2016.02.

Key Topics

• Scope & applicability: Fortified milk powders, infant formulas and nutritionally complete adult liquid products, in powder or liquid form.
• Sample preparation: Dispersion in sodium phosphate buffer, autoclaving (121 °C for 25 min), centrifugation and filtration to obtain a clear extract.
• Immunoaffinity clean‑up: Use of a biotin immunoaffinity column mounted on an SPE manifold to selectively retain biotin/biocytin prior to elution.
• Chromatography & detection: HPLC analysis with a photodiode array (PDA) detector (200 nm) for simultaneous identification and quantification; quantification by multipoint external calibration using peak area.
• Reagents & standards: Instructions for preparing buffers, mobile phases, and calibration standards; use of high‑purity biotin and biocytin reference materials.
• Quality control & performance: Includes precision (repeatability and reproducibility) data in Annex B, limit of quantitation guidance and a comparison to EN 15607 (Annex C).
• Safety note: The method involves hazardous materials and equipment; users must establish appropriate lab safety practices.

Applications

ISO 23305:2020 is intended for:

• Food testing laboratories performing nutritional analysis of infant formulas, fortified milk powders and adult nutritionals.
• Manufacturers conducting in‑house quality control and formulation verification for biotin fortification.
• Regulatory authorities and third‑party accreditation bodies validating label claims and compliance with nutritional standards.
• Research institutions studying vitamin stability and bioavailability in dairy and nutritional products.

Practical benefits include selective immunoaffinity cleanup to reduce matrix interference, robust HPLC quantification, and harmonized precision data enabling cross‑laboratory comparability.

Related Standards

• EN 15607 - comparative data provided in Annex C.
• AOAC Official Method 2016.02 - method equivalence noted in the ISO foreword.
• ISO/TC 34 (Food products) - technical committee responsible for development.

Keywords: ISO 23305:2020, biotin determination, fortified milk powders, infant formula, adult nutritionals, liquid chromatography, immunoaffinity column, HPLC, analytical method, food safety, nutritional labelling.