Ion-chromatographic methods have also been widely studied for the separation of nitrite and nitrate and other ions in several matrices [20], [21] and [22]. Ion-pair HPLC methods offer, with respect to ion chromatography, advantages of relatively lower cost in instrumentation and columns and can be advantageously employed in laboratories where only conventional HPLC systems are available. Additionally, the theoretical column efficiency of ion-pair HPLC is better than that of an IC column, assuming that a suitable ion-pair reagent is chosen. However, little information is available on the analysis of residual nitrite and nitrate in food samples using ion-pair HPLC.