Modification of AOAC method 973.31 for determination of nitrite in cured meats

• Published in: Journal of AOAC International 2008-07, Vol.91 (4), p.820-825
• Main Authors: Mohamed, Ashraf A, Mubarak, Ahmed T, Fawy, Khaled F, El-Shahat, Mohamed F
• Format: Article
• Language: English
• Subjects: accuracy; analytical methods; Biological and medical sciences; Buffers; Calibration; correlation; cured meats; detection limit; Diazonium Compounds - analysis; filtration; food composition; food contamination; Food Handling; Food industries; Fundamental and applied biological sciences. Psychology; hot water treatment; Hydrogen-Ion Concentration; Indicators and Reagents; laboratory techniques; Meat - analysis; Meat and meat product industries; new methods; nitrites; Nitrites - analysis; precision; quantitative analysis; reproducibility; soaking; Spectrophotometry, Ultraviolet; statistical analysis; Sulfanilamide; Sulfanilamides - analysis; Temperature; validity
• ISSN: 1060-3271; 1944-7922
• DOI: 10.1093/jaoac/91.4.820

A modification of AOAC Method 973.31 is proposed to improve the extraction efficiency of nitrite from cured meat samples and its subsequent quantification based on the diazotization-coupling reaction of sulfanilamide with N-(1-naphthyl)ethylenediamine dihydrochloride (NED). The various experimental parameters were thoroughly investigated. A 5 g meat sample was mixed with 400 mL water; the pH of the mixture was adjusted to 5.5 +/- 0.3 and allowed to stand for 2 h on a water bath at 80 degrees C, with occasional shaking for the complete extraction of nitrite. After quantitative filtration, an aliquot was mixed with chloroacetic-chloroacetate buffer, pH 1.80 +/- 0.05, sulfanilamide, and NED, and the absorbance of the resulting azodye was recorded at 540 nm against water as a reference. Following the recommended procedure, a linear calibration graph was obtained for up to 0.8 [micro]g/mL NO2-, with a correlation coefficient of 0.9996 and a detection limit (based on the 3 Sb-criterion) of 5.6 ng/mL NO2-. The proposed method was conveniently applied to various cured meat samples and was validated by comparison with the original AOAC method and by recovery experiments that gave quantitative results (94-98%) with convenient reproducibility. Statistical analysis of the analytical data could not detect any systematic error and revealed the high accuracy and precision of the proposed method.