Overview
EN ISO 13366-1:2008 (ISO 13366-1:2008 / IDF 148-1:2008) specifies the microscopic reference method for the enumeration of somatic cells in milk. The standard covers counting somatic cells in both raw and chemically preserved milk, and is applicable to cows' milk when prerequisites are met. It is intended as the reference procedure for preparing standard test samples and for establishing reference values used to calibrate mechanized and automated cell-counting methods.
Key topics and requirements
- Principle: A measured test portion is spread as a smear on a microscope slide, dried while cells are stained, and stained cells are counted in a defined area. Results are converted to cells per millilitre using a working factor.
- Scope: Counting of somatic cells (leucocytes and epithelial cells with nuclei) in raw and preserved cows' milk.
- Reagents: Includes dye solutions such as the Modified Newman–Lampert stain (Levowitz–Weber modification) and ethidium bromide staining protocols, plus Phosphate Buffer Solution (PBS). The standard warns about hazards (e.g., tetrachloroethane is poisonous; ethidium bromide is mutagenic) and mandates appropriate safety controls.
- Apparatus & sampling: Provides guidance on required equipment, sampling, sample storage and preparation of test samples and smears.
- Procedure: Detailed steps for smear preparation, staining, microscopic counting, and calculation procedures (including different counting grid shapes).
- Quality and performance: Sections on precision (repeatability and reproducibility), calculation and expression of results, and reporting requirements.
Applications and users
This standard is essential for:
- Dairy laboratory analysts performing authoritative somatic cell counts (SCC) for quality monitoring.
- Milk processors and quality-control teams ensuring compliance with regulatory limits and herd health monitoring.
- Regulatory bodies and certification agencies that require reference-method traceability.
- Manufacturers of automated and mechanized somatic cell counters, who use ISO 13366-1 to calibrate instruments and validate performance.
- Research laboratories studying milk quality, mastitis prevalence, or method comparison studies.
Key practical benefits include producing reference-standard test samples, ensuring comparability between laboratories, and providing a validated basis for calibrating high-throughput automated SCC instruments.
Related standards
- ISO 13366-2 - Guidance on the operation of fluoro-opto-electronic counters (complements Part 1).
- Published jointly as ISO 13366-1 | IDF 148-1:2008 and endorsed as EN ISO 13366-1:2008 for CEN members.
Keywords: ISO 13366-1:2008, EN ISO 13366-1, somatic cell count, SCC, microscopic method, milk quality, reference method, calibration, Newman–Lampert, ethidium bromide.
