Spectrophotometric determination of nitrite in foodstuffs by flow injection analysis

Abstract

A simple method for the determination of nitrite in foodstuffs by flow injection analysis is described. Nitrite samples are prepared in a microwave oven, treated with a 1 mol/l NH(4)Cl solution at a pH of 9 (all under nitrogen atmosphere) and are immediately analysed. Nitrite is diazotised in the FIA system with N-(1-naphthyl) ethylenediammonium dichloride to form the highly coloured azo dye, which is measured at 540 nm. The detection limit is 0.036 mg/kg for sample injections of 400 microl. The sampling rate is about 50 samples per hour and the relative standard deviation is 0.67%.

Sequential injection spectrophotometric analysis of nitrite in natural waters using an on-line solid-phase extraction and preconcentration method

“…Samples of pH ranging between 5.5-8 were analysed without delay to avoid nitrite decomposition. 16 Both in tap and rain water, the nitrite content was below the detection limit of the system, but matrix interference was not observed. These samples were spiked and the accuracy of the linear regression, in terms of the amounts of nitrite for different sample volumes, was assessed.…”

“…Shinn's proposal 10 to use sulfanilamide and N-(1-naphthyl)ethylenediamine dihydrochloride as diazotization and coupling reaction reagents, respectively, has been the basis of many FIA spectrophotometric methods. [11][12][13][14][15][16][17] The same reaction has been employed in continuous systems for the determination of nitrite traces in liquid samples by means of a flow-through optical sensor 18 and as post-column reaction in ion chromatography. 19 FIA spectrophotometric methods of only one step based on either the use of coloured diazotization reagents 20,21 or on C-nitrosation reactions 22 have also been reported.…”

Determination of Nitrite from Water Catchment Areas Using Graphite Based Electrodes

“…0.2 mol L −1 buffer acetate solution was used at the following different pH's: pH = 3.6; 4; 4.6; 5 and 5.6. A standard stock solution of 1.00 × 10 −2 mol L −1 nitrite was prepared by dissolving 0.1725 g of sodium nitrite in 250 mL deionized water using the same precautions as previously described 32,33 and stored in a refrigerator. This is equivalent to 460 mg L −1 of nitrite in the stock solution.…”

Quantification of Nitrite/Nitrate in Food Stuff Samples Using 2-Aminobenzoic Acid as a New Amine in Diazocoupling Reaction

“…Both of these ions occur wide spread contaminants in aqueous environment and serve as significant indicators of quality of natural waters. The increasing level of nitrate in ground water results mainly from agricultural application of fertilizers as well as from many industrial processes (Van Staden and Makhafola 1996). Nitrate is one of the principal nutrients which stimulates the growth of macrophytes and phytoplankton present in water causing eutrophication.…”