Determination of Nitrite and Nitrate in Meet Products by Inline Dialysis Ion Chromatography

A determination method of nitrate and nitrite in foodstuffs using ion chromatography (IC) equipped with an inline dialysis system is presented. The conditions of the inline dialysis system were optimized for the simultaneous extraction of nitrate and nitrite. Under the optimized conditions, the detection limits (S/N = 3) for nitrate and nitrite when injecting 20 mu L with UV detection were 0.08 mg L(-1) and 0.05 mg L(-1) respectively. The linear range of both ions was over 3 orders of magnitude, from 0.1 mg L(-1) to 20 mg L(-1). The relative standard deviation (RSD, n = 10) for nitrate and nitrite in sausage was 2.43% and 1.57%, respectively. The inline dialysis system combined with IC was applied to the simultaneous determination of nitrate and nitrite in foodstuffs, such as ham and sausage, and was compared to the determined values obtained by a solid-phase extraction-IC method and an enzyme-reduction spectrometric method. Good correlations for both ions between the inline-dialysis-IC method and the enzyme reduction spectrometric method were obtained. However, the results of the solid-phase extraction-IC method and the inline-dialysis-IC method did not show a good correlation, because the matrices could not be removed very well, and interfered with measurements in the solid extraction - IC method. The present method will be useful for the determination of inorganic ions in food samples containing high-concentration matrixes.