Voltammetric determination of nitrite in meat products using polyvinylimidazole modified carbon paste electrode

A simple and sensitive voltammetric method was developed to determine the amount of nitrite by using Carbon Paste Electrode (CPE) which is modified with polyvinylimidazole (PVI). A buffer solution of phosphate with a pH 4 value was used in the experiments. The amount of the nitrite-ion was determined by cyclic voltammetry (CV). The electro-chemical behaviour of nitrite-ion was investigated by using CV on the PVI modified CPE. A well-defined oxidation peak was obtained at 0.83 V against a reference Ag/AgCl electrode. Differential pulse voltammetry (DPV) was applied for the calibration plot and for the detection limit. The optimisation procedure was done in two steps: using a two-level factorial design for preliminary evaluation of the contributing factors, and the Box-Behnken Design (BBD) to assess the optimal experimental conditions. These are done with the analysis of 3 different factors in 15 runs of DPV. The optimum conditions are obtained within a linear response range of 5 × 10^-7-1 × 10^-4 mol L^-1. Regression analysis is performed within this range showed the linear equation of y = 0.028x + 3.93 × 10^-7 with r² = 0.9982, and for n = 7. Limit of Detection (LOD) was 9 × 10^-8 mol L^-1 with S/N = 3, and Limit of Quantification (LOQ) was 3 × 10^-7 mol L^-1 with S/N = 10. The procedure was used successfully to detect the amount of nitrite in meat products.