🍎 Nitrites and nitrates in meat
In short
Determination of nitrites (NO₂⁻) and nitrates (NO₃⁻) in meat and meat products. The test is performed according to PN-EN 12014-2:2001; Measurement range: 1–1000 mg/kg. The procedure comprises 5 steps (about 1 h 15 min in total); it is used for: Control of curing salt use in meat (EU Reg. 1333/2008), Analysis of cured meats, sausages, bacon, and ham, Food safety monitoring (residual nitrites).
At a glance
- Standard: PN-EN 12014-2:2001
- Category: Food Chemistry
- Procedure steps: 5
- Total time of stages: 1 h 15 min
- Ions determined: NO₂⁻ (nitrites), NO₃⁻ (nitrates)
- Measurement range: 1–1000 mg/kg
- Limit of detection: 0.5 mg/kg
Overview
Nitrites (E249, E250) and nitrates (E251, E252) are used as curing agents in meat processing — they give the characteristic pink color to cured meats, inhibit Clostridium botulinum growth, and affect flavor. However, excess nitrites are toxic (methemoglobinemia) and can lead to nitrosamine formation (carcinogenic).
EU Reg. 1333/2008 establishes limits: NaNO₂ max 150 mg/kg (as nitrite ions), NaNO₃ max 150–300 mg/kg (as nitrate ions, depending on product). HPLC/IC method allows simultaneous determination of both forms.
Method principle
Meat sample is homogenized with warm water (70°C), deproteinated with Carrez reagents, filtered, and analyzed by ion chromatography (IC) with conductometric detection or HPLC with UV detection (210–220 nm). Nitrites and nitrates are separated on an anion-exchange column. Identification based on retention times, quantitative determination using a calibration curve.
Applications
- Control of curing salt use in meat (EU Reg. 1333/2008)
- Analysis of cured meats, sausages, bacon, and ham
- Food safety monitoring (residual nitrites)
- Quality control in meat plants
- Analysis of vegetables (naturally high nitrate levels)
Key parameters
| Parameter | Value |
|---|---|
| Ions determined | NO₂⁻ (nitrites), NO₃⁻ (nitrates) |
| Measurement range | 1–1000 mg/kg |
| Limit of detection | 0.5 mg/kg |
| NaNO₂ limit in meat | 150 mg/kg (as nitrite ions) |
| Precision (CV) | 3–8% |
Standard
- Standard number
- PN-EN 12014-2:2001
- Title (PL)
- Artykuły żywnościowe — Oznaczanie azotanów(III) i/lub azotanów(V) — Część 2: Metoda HPLC/IC
- Title (EN)
- Foodstuffs — Determination of nitrate and/or nitrite content — Part 2: HPLC/IC method
Step-by-step procedure
-
Extraction
Weigh 10 g homogenized meat. Add 60 mL warm water (70°C). Mix 30 min in 70°C bath.
-
Deproteination
Cool to 20°C. Add 2 mL Carrez I + 2 mL Carrez II. Fill to 100 mL. Mix.
-
Filtration
Filter through paper filter, then 0.22 µm into IC vial.
-
IC analysis
Anion-exchange column, eluent: Na₂CO₃/NaHCO₃, conductometric detection or UV 210 nm.
-
Calculations
Convert to mg/kg NaNO₂ and NaNO₃ in product. Compare with limits.
Required equipment and apparatus
| Equipment | Example | Indicative price |
|---|---|---|
| Ion chromatograph / HPLC-UV | Thermo Dionex Aquion, Metrohm 930 Compact IC Flex | 120 000–280 000 PLN |
| Anion-exchange column | Thermo AS22, Metrohm Metrosep A Supp 5 | 3 000–6 000 PLN |
| Homogenizer | IKA Ultra-Turrax T25 | 5 000–15 000 PLN |
| Water bath 70°C | GFL 1003 | 3 000–8 000 PLN |
Reagents, media and consumables
| Reagent | CAS | Details |
|---|---|---|
| Sodium nitrite NaNO₂ (standard) | 7632-00-0 | CRM 1000 mg/L NO₂⁻ |
| Potassium nitrate KNO₃ (standard) | 7757-79-1 | CRM 1000 mg/L NO₃⁻ |
| Carrez I and II reagents | — | For deproteination of meat samples |
| Deionized water | — | >18 MΩ·cm |
Health and safety (OHS)
- Sodium nitrite — toxic (T+), oxidizer. Gloves, safety glasses, fume hood.
- Do not mix with acids — release of toxic nitrogen oxides (NOₓ)
- Meat samples — disposable gloves, cold chain
Frequently asked questions
Which standard describes this test?
The test is performed according to PN-EN 12014-2:2001 — “Foodstuffs — Determination of nitrate and/or nitrite content — Part 2: HPLC/IC method”.
How does this method work?
Meat sample is homogenized with warm water (70°C), deproteinated with Carrez reagents, filtered, and analyzed by ion chromatography (IC) with conductometric detection or HPLC with UV detection (210–220 nm). Nitrites and nitrates are separated on an anion-exchange column.
What is the measuring range and accuracy?
Ions determined: NO₂⁻ (nitrites), NO₃⁻ (nitrates); Measurement range: 1–1000 mg/kg; Limit of detection: 0.5 mg/kg; NaNO₂ limit in meat: 150 mg/kg (as nitrite ions).
How long does the test take?
The times given for the individual stages add up to approximately 1 h 15 min. The procedure comprises 5 steps.
What equipment is required?
Ion chromatograph / HPLC-UV, Anion-exchange column, Homogenizer, Water bath 70°C. Indicative cost of the core instrument (Ion chromatograph / HPLC-UV): 120 000–280 000 PLN.
Where is this test used?
Control of curing salt use in meat (EU Reg. 1333/2008); Analysis of cured meats, sausages, bacon, and ham; Food safety monitoring (residual nitrites); Quality control in meat plants; Analysis of vegetables (naturally high nitrate levels).
What safety precautions apply?
Sodium nitrite — toxic (T+), oxidizer. Gloves, safety glasses, fume hood.; Do not mix with acids — release of toxic nitrogen oxides (NOₓ); Meat samples — disposable gloves, cold chain.
Which laboratory can perform this test?
The test is performed by laboratories accredited to ISO/IEC 17025. On LabCoda you can find them by the standard number PN-EN 12014-2.