Spectrophotometric Determination of Nitrite and Nitrate in Cured Meat by Sequential Injection Analysis

Abstract

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-NO 2 -and 0.034 to 3.95 mg/L of N-NO 3 -ranges, respectively, at a sampling rate of 9/h. Detection limits of 9 g/L of N for nitrite and 9 g/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.

Evaluating the Residual Nitrite Concentrations of Bacon in the United Kingdom

“…Conversely, studies conducted in Brazil, South Korea, and Australia reported levels over 2 times higher than that of this study. Twenty-one samples of Brazilian processed meat were analysed for residual nitrite concentrations and the mean value was reported as 22.4 mg/kg, and when stratifying the samples by type of processed meat, ham had an average value of 47.25 mg/kg and dry cured ham had a value of 9.4 mg/kg [ 17 ]. An in vitro study of bacterial growth on media treated with sodium chloride reported that a sample of bacon from South Korea had a residual nitrite concentration of 26 mg/kg, although the method of analysis was unclear [ 18 ].…”

A sensitive fluorimetric method for determination of trace amounts of nitrite based on luminescence energy transfer

“…[41]The determination was in water, cell culture media, plasma and urine. [42] The samples were cured meat samples. [43] LOD was measured in aqueous samples.…”

Rapid and sensitive method for analysis of nitrate in meat samples using ultra performance liquid chromatography–mass spectrometry

“…Alonso et al [19] reported spectrophotometric method involving borax, potassium ferrocyanide, zinc acetate and acetic acid with a LOD of 9 mg kg À1 and an analysis time of around 30 min. Sequential Injection spectrophotometric analysis was performed by Oliveira et al [20] with LOD of 9 lgL À1 and a linear range of 0.034-3.95 mg L À1 , although the reported method is sensitive yet it is time taking as stock solution preparation takes more than 2 h. Spectrophotometric method reported by Zartar et al is also time consuming with more than 2 h sample preparation step and 30 min of analysis time [21]. Other procedure involving flow injection analysis has reported 20 mg kg À1 LOD and a recovery of 93-110%.…”

“…Several methods have been developed to quantitate nitrate in meat including HPLC [13][14][15][16][17][18][19][20], spectrophotometry [21][22][23][24][25], potentiometric [26,27], capillary electrophoresis [28][29][30]. Full automated Robotic method has been reported for the estimation of nitrate in cured meat sample [31].…”