Spectrophotometric determination of nitrite and nitrate in cured meat by sequential injection analysis

S. M. Oliveira, T. I. M. S. Lopes, A. O. S. S. Rangel*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

30 Citations (Scopus)


A robust, automated, labor-saving, accurate, and economical sequential injection system was developed for simultaneous determination of nitrite and nitrate in cured meat samples, based on the Shinn reaction. Nitrite is coupled and diazotized with sulfanilamide and N-(1-naphtyl)-ethylenediamine dihydrochloride, to form a colored compound that absorbs at 538 nm. Nitrate is previously in-line reduced to nitrite in a copperized cadmium column and measured as nitrite. The solutions' aspiration sequence, the influence of reagent and buffer concentrations, the manifold parameters, and the characteristics of the reducing column were studied. Nitrite and nitrate can be determined within the 0.030 to 1.22 of N-NO2- and 0.034 to 3.95 mg/L of N-NO3- ranges, respectively, at a sampling rate of 9/h. Detection limits of 9 μg/L of N for nitrite and 9 μg/L of N for nitrate were obtained, and the conversion rate of nitrate to nitrite was 100.6% ± 1.8%. The results were in good agreement with those obtained by the reference methods, with relative standard deviations (r.s.d.) better than 3.70% for nitrites and 2.42% for nitrates.

Original languageEnglish
Pages (from-to)C690-C695
Number of pages6
JournalJournal of Food Science
Issue number9
Publication statusPublished - Nov 2004


  • Copperized cadmium column
  • Meat
  • Nitrate
  • Nitrite
  • Sequential injection analysis
  • Spectrophotometry


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