title: Modification of AOAC method 973.31 for determination of nitrite in cured meats.
abstract: 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 microg/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.
authors: Ain Shams University, Faculty of Science, Department of Chemistry, Abbassia, Cairo-11566, Egypt. aamohamd@hotmail.com
authors: Ashraf A
authors: AA
authors: Mohamed
authors: Ahmed T
authors: AT
authors: Mubarak
authors: Khaled F
authors: KF
authors: Fawy
authors: Mohamed F
authors: MF
authors: El-Shahat
mesh_terms: D002021:Buffers; D002138:Calibration; D003979:Diazonium Compounds / Q000032:analysis; D005511:Food Handling; D006863:Hydrogen-Ion Concentration; D007202:Indicators and Reagents; D008460:Meat / Q000032:analysis*; D009573:Nitrites / Q000032:analysis*; D013056:Spectrophotometry, Ultraviolet; D000077145:Sulfanilamide; D013424:Sulfanilamides / Q000032:analysis; D013696:Temperature
chemical_list: D002021:Buffers; D003979:Diazonium Compounds; D007202:Indicators and Reagents; D009573:Nitrites; D013424:Sulfanilamides; D000077145:Sulfanilamide