Simultaneous determination of nitrite, nitrate and ascorbic acid in canned vegetable juices by reverse-phase ion-interaction HPLC.

A simple ion-interaction C18 reverse-phase high performance liquid chromatographic method was developed for simultaneous determination of nitrite, nitrate and ascorbic acid in canned vegetable juices. The method makes use of 0.010 M octylammonium orthophosphate as the ion interacting reagent and 20% (v/v) aqueous methanol as the mobile phase. The content of nitrite, nitrate (expressed as nitrite ion and nitrate ion, respectively) and ascorbic acid in commercial brands of canned tomato, carrot and mixed vegetable juices were surveyed. The quantitative results indicated that nitrite was very probably added as a preservative in the canned vegetable juices. The total amount of nitrite and nitrate ion per can in two commercial brands of vegetable juices was found to exceed the acceptable daily intake recommended by the 1996 Joint FAO/WHO Expert Committee on Food Additives for an average adult of 60 kg body weight.