Overview
ISO 13366-2:2006 (IDF 148-2:2006) provides practical guidance on the operation of fluoro-opto-electronic somatic cell counters for milk. It covers operating conditions for counting somatic cells in both raw and chemically preserved milk using instruments that employ either a rotating disc (disc cytometry) technique or flow cytometry in the counting section. The guidance is primarily for raw cow milk but can be applied to goat, sheep and buffalo milk when the specified prerequisites are met.
Key topics and technical requirements
- Principle of measurement: description of mixing test sample with buffer and fluorescent stain, and detection of stained cell nuclei by optical/electronic pulse processing.
- Counting technologies: rotating disc (disc cytometry) and flow cytometry; some instruments may have dual channels which must be evaluated separately.
- Sampling and sample handling: clean containers, representative sampling of bulk and individual milkings, cooling (0–6 °C) and avoidance of freezing.
- Chemical preservation: permitted preservatives and maximum concentrations (boric acid, sodium azide, bronopol, potassium dichromate) and recommended storage times/temperatures; acceptable colour tracers.
- Instrument operation and calibration: dosing and mixing control, discriminator settings (fixed or dynamic), working factor, test volumes, and use of reference materials and calibration procedures.
- Quality assurance and performance checks: blank checks, carry-over assessment, reagent/sample ratio checks, pilot checks, repeatability, intralaboratory reproducibility and external comparisons.
- Species-specific remarks and precision: specific considerations for cow, goat, sheep and buffalo milk and sections on repeatability, reproducibility and test reporting.
Applications and users
ISO 13366-2 is intended for:
- Dairy laboratories implementing somatic cell counting with automated fluoro-opto-electronic counters.
- Quality managers and technicians responsible for milk quality control, mastitis monitoring and compliance with regulatory or trade limits.
- Instrument manufacturers and service engineers validating instrument performance, calibration and troubleshooting.
- Regulatory agencies and laboratories conducting proficiency testing and method validation.
Practical benefits include improved consistency of somatic cell counts, harmonized procedures for sample preservation and transport, and structured quality control to support reliable milk hygiene and dairy herd health decisions.
Related standards
- ISO 13366-1 / IDF 148-1 - Microscopic method (reference method)
- ISO 8196-1 / IDF 128-1 and ISO 8196-2 / IDF 128-2 - Accuracy, calibration and quality control for indirect milk methods
- ISO Guide 34 and ISO Guide 43-1 - reference materials and proficiency testing
Keywords: ISO 13366-2:2006, somatic cells, fluoro-opto-electronic counters, somatic cell counting, flow cytometry, disc cytometry, milk quality, dairy laboratory.