Detection of nitrate and nitrite in different seafood

High-performance ion-exchange chromatography with suppressed conductivity (HPIEC-SCD) was validated for the determination of nitrite (NO2 -) and nitrate (NO3 -) in the edible part of diverse seafood species. Samples analyzed by HPIEC-SCD that were devoid of nitrite and nitrate were subjected to HRMS using a Q-exactive Orbitrap platform. As NO2 - is not detectable in Q-Exactive Orbitrap, it was necessary to perform the oxidation of NO2 - to NO3 -. Accordingly, suitability of NO2 - oxidation by H2O2 as a part of sample preparation for HPIEC-HRMS was elaborated. The difference in the concentration of NO3 - before and after H2O2 treatment was used for the evaluation of eventual NO2 - presence. The edible part of 53 fish, shrimp and bivalve species presented significant differences in NO3 - levels especially between farmed (median=44μg/g) and wild species (median=16μg/g). The highest concentration of NO3 - was found in smoked salmon samples (median=60μg/g) while NO2 - was not revealed in any of the samples studied.