Overview - ISO 23970:2021 (Milk, milk products and infant formula)
ISO 23970:2021 specifies a validated analytical method for the determination of melamine and cyanuric acid in milk, milk products and infant formula using liquid chromatography coupled with tandem mass spectrometry (LC‑MS/MS). The method was validated in an interlaboratory study on matrices including milk‑based and soy‑based infant formula, milk powder, whole milk, soy drink and milk chocolate. Reported limits of quantification (LOQ) are 0.05 mg/kg for melamine and 0.25 mg/kg for cyanuric acid; the working range extends up to 10 mg/kg (melamine) and 25 mg/kg (cyanuric acid).
Key topics and technical requirements
- Analytical technique: LC‑MS/MS with triple quadrupole mass spectrometry; compatible with HPLC or UHPLC.
- Chromatography: Hydrophilic interaction liquid chromatography (HILIC) separation.
- Ionization & detection: Electrospray ionization (ESI) and multiple reaction monitoring (MRM) transitions for specific, sensitive quantification.
- Internal and recovery standards: Use of 13C‑labelled internal standards for melamine and cyanuric acid, and benzoguanamine as a recovery standard to ensure accurate quantitation.
- Validated matrices & ranges: Method performance demonstrated for infant formulas, milk powders, whole milk, soy drink and milk chocolate at spiking levels ~0.57–1.45 mg/kg (cyanuric acid) and ~0.71–1.43 mg/kg (melamine).
- Reagents & sample prep: Specified reagent grades (e.g., LC‑MS grade solvents, formic acid, ammonium acetate) and stepwise sample extraction, centrifugation and injection procedures.
- Quality criteria: Calibration, identification, recovery and precision criteria defined; method precision assessed through repeatability and reproducibility data.
Applications - who uses ISO 23970:2021
- Food testing laboratories performing routine monitoring and compliance testing for melamine contamination in dairy products and infant formula.
- Regulatory and public health agencies assessing food safety and responding to contamination incidents.
- Dairy manufacturers and quality assurance teams implementing analytical controls for supply chain safety.
- Accredited testing facilities seeking an ISO/IDF validated LC‑MS/MS method for laboratory accreditation and proficiency testing.
Related standards
- ISO 3696 - Water for analytical laboratory use (referenced for reagent water quality).
- ISO/IDF joint methods for analytical testing of milk products (consult national bodies for other relevant dairy testing standards).
This standard is essential for accurate, sensitive detection of melamine and cyanuric acid in dairy matrices using LC‑MS/MS and supports regulatory compliance, food safety monitoring, and laboratory quality systems.