Overview
EN ISO 14673-1:2004 (ISO 14673-1:2004 / IDF 189-1:2004) specifies an internationally accepted analytical method for determining nitrate and nitrite in milk and milk products. The standard covers sample preparation, cadmium-reduction chemistry, spectrometric measurement and calculation steps for a wide range of dairy matrices including dried milks, hard/soft/processed cheeses, whey cheese, caseins/caseinates and dried whey. The procedure can be performed manually or automated to reduce cadmium handling and laboratory contamination.
Key topics and technical requirements
- Scope and applicability: Whole, partly skimmed and skimmed dried milk; hard, semi-hard and soft cheeses; processed cheese; whey cheese; caseins and caseinates; dried whey.
- Analytical principle: Reduction of nitrate (NO3–) to nitrite (NO2–) using a copperized cadmium column, followed by diazotization–coupling with sulfanilamide and N‑1‑naphthyl ethylenediamine dihydrochloride to develop a coloured azo dye measured by spectrometry (wavelength ~538 nm).
- Sample prep: Dispersion in warm water, fat/protein precipitation, filtration and deproteination prior to analysis.
- Quality controls: Blank tests, calibration graph preparation, checks of cadmium column reducing capacity and column regeneration procedures.
- Automation options: Method can be applied using segmented flow analysis (SFA) or flow injection analysis (FIA) to improve throughput and reduce cadmium waste and workplace exposure.
- Safety and environmental considerations: Cadmium is hazardous - the standard highlights safe handling, minimizing laboratory contamination and reducing cadmium in wastewater via automation and appropriate waste control.
- Data reporting: Calculation and expression of results as mg NO3–/kg and mg NO2–/kg; sections on precision, repeatability and test reporting are included.
Applications and practical value
- Routine dairy quality control and internal lab testing for nitrate/nitrite residues.
- Food safety and regulatory testing where authorities require validated methods for nitrate/nitrite in dairy products.
- Research laboratories studying minor inorganic contaminants in milk and derived products.
- Useful when a validated, internationally harmonized spectrometric cadmium-reduction method is required, or when transitioning to automated SFA/FIA for higher throughput and lower cadmium exposure.
Who should use this standard
- Dairy industry QC/analytical laboratories
- National and regional food control laboratories
- Third‑party testing laboratories and contract analysis providers
- Regulatory authorities and standardization committees
Related standards
- ISO 14673-2 / IDF 189-2 - Segmented flow analysis (routine method)
- ISO 14673-3 / IDF 189-3 - Flow injection analysis with in-line dialysis (routine method)
- Referenced glassware and sampling standards (e.g., ISO 1042)
Keywords: EN ISO 14673-1:2004, milk and milk products, nitrate determination, nitrite determination, cadmium reduction, spectrometry, segmented flow analysis, flow injection analysis, dairy testing, analytical method.
