Overview
EN ISO 14673-2:2004 (ISO 14673-2 | IDF 189-2:2004) specifies a routine laboratory method for the determination of nitrate and nitrite in milk and milk products using segmented flow analysis (SFA). The standard applies to fresh milk, cheese, liquid and dried milk products and infant foods. Results are expressed as mass fractions (mg/kg) of nitrate (NO3−) and nitrite (NO2−).
Key topics and technical requirements
- Scope and applicability: Routine method for dairy matrices including infant foods; part of the ISO 14673 series covering nitrate/nitrite analysis in dairy.
- Principle:
- Nitrate: sample is suspended in water, dialysed in the analyser, nitrate ions are reduced to nitrite, then measured spectrometrically. Any native nitrite is determined as nitrate unless corrected.
- Nitrite: sample is suspended in an ammonium/sodium chloride solution, dialysed, and measured spectrometrically against nitrite standards.
- Sampling & sample preparation: specific procedures for cheese, dried milk products/infant food, and liquid milk products to create representative test portions.
- Reagents & apparatus: standard laboratory reagents and equipment for SFA, dialysis modules and a reducing column (prepared and checked per the method).
- Analytical procedure: includes preparation and quality-checking of the reduction column, SFA runs, calibration curve construction, and drift checks of standards.
- Quality control: calibration with standards, drift monitoring, and precision data are specified; the method gives instructions for calculation and expression of results.
- Documentation: required contents of the test report are defined to ensure traceability and comparability.
Practical applications and users
- Food and dairy testing laboratories performing routine screening and quantification of nitrate and nitrite in milk, cheese and infant formulas.
- Dairy industry quality-control teams verifying raw material and product compliance.
- Regulatory authorities and food safety inspectors assessing compliance with legal limits and monitoring programs.
- Infant food manufacturers validating product safety (noting soy-based infant foods may require special consideration for nitrite).
- Analytical equipment suppliers and method developers implementing segmented flow analysers for routine dairy testing.
Related standards
- ISO 14673-1: Method using cadmium reduction and spectrometry (alternative method).
- ISO 14673-3: Method using cadmium reduction with flow injection analysis and in-line dialysis.
- Normative references for laboratory glassware: ISO 648, ISO 835‑1, ISO 1042.
Keywords: EN ISO 14673-2, ISO 14673-2:2004, nitrate nitrite analysis, segmented flow analysis, milk testing, dairy quality control, infant food nitrate.