Rapid determination of nitrites in food using a diffuse UV-visible reflectance method.
A simple, low-cost, sensitive and selective method for the determination of trace quantities of nitrite in foods such as cheese and cured meat using diffuse ultraviolet-visible reflectance was developed. It is based on the reaction of nitrite with sulphadiazine and α-naphthol, which produces a coloured product in basic medium. The reaction is carried out directly in the measuring cell. For cheese the limit of detection (LOD), expressed as NaNO₂, was estimated to be about 2.0 × 10⁻²mg l⁻¹ (2.9 × 10⁻⁷mol l⁻¹) in the final measuring solution and 0.17 mg kg⁻¹ in cheese (2.5 × 10⁻⁶mol kg⁻¹). The relative standard deviation (RSD) varied from 5% to 8% depending on the sample. For meat the LOD was estimated to be about 2.0 × 10⁻²mg l⁻¹ (2.9 × 10⁻⁷mol l⁻¹) in the final measuring solution and 0.13 mg kg⁻¹ in meat (1.9 × 10⁻⁶mol kg⁻¹). The RSD varied from 3% to 6% depending on the sample. The results of the proposed method were also compared with those obtained with the official method using the statistical Student's t-test and F-test procedures.
Institute of Chemistry, University of Campinas, PO Box 6154, 13083-970 Campinas, SP, Brazil.
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D001938:Brazil; D002273:Carcinogens / Q000032:analysis*; D002611:Cheese / Q000032:analysis*; D005513:Food Inspection / Q000379:methods*; D005520:Food Preservatives / Q000032:analysis*; D057230:Limit of Detection; D008460:Meat / Q000032:analysis*; D009573:Nitrites / Q000032:analysis*; D015203:Reproducibility of Results
D002273:Carcinogens; D005520:Food Preservatives; D009573:Nitrites