Rapid determination of nitrites in food using a diffuse UV-visible reflectance method

Area of Science:

• Analytical Chemistry
• Food Science
• Spectroscopy

Background:

• Nitrite is a common food additive and preservative, particularly in cured meats.
• Accurate quantification of nitrite is crucial for food safety and regulatory compliance.
• Existing methods for nitrite determination can be complex or costly.

Purpose of the Study:

• To develop a simple, low-cost, sensitive, and selective method for determining trace nitrite in food matrices.
• To utilize diffuse ultraviolet-visible (UV-Vis) reflectance spectroscopy for nitrite quantification.
• To validate the method's performance in real food samples like cheese and cured meat.

Main Methods:

• A colorimetric reaction between nitrite, sulphadiazine, and α-naphthol in a basic medium was employed.
• The colored product was measured directly in the measuring cell using diffuse UV-Vis reflectance.
• The method was applied to cheese and cured meat samples, with results compared to official methods using statistical tests.

Main Results:

• The method demonstrated high sensitivity with a limit of detection (LOD) of 0.17 mg/kg for cheese and 0.13 mg/kg for meat (expressed as NaNO₂).
• Relative standard deviations (RSD) were low, ranging from 5-8% for cheese and 3-6% for meat, indicating good precision.
• Statistical analysis (Student's t-test and F-test) confirmed good agreement between the proposed method and the official method.

Conclusions:

• The developed diffuse UV-Vis reflectance method is a viable, simple, and cost-effective technique for accurate trace nitrite determination in foods.
• This method offers a sensitive and selective alternative for routine food analysis, ensuring food safety.
• The technique's direct measurement in the cell simplifies the analytical procedure.