Determination of nitrates, nitrites and oxalates in food products by capillary electrophoresis with pH-dependent electroosmotic flow reversal

This paper describes an innovative and rapid capillary electrophoretic method for the simultaneous analysis of nitrates. nitrites and oxalates, which are anions of food interest. The novelty of our method is based on reversing the electroosmotic flow without using any buffer additive nor performing a capillary coating, but simply employing a buffer at low pH values. The analytical conditions have been optimised and the proposed method has been fully validated following the EURACHEM guidelines. The method has been successfully applied to the analysis of different vegetable samples: furthermore nitrates' content has been evaluated for the first time in table sugars and dietary fibres. A comparison of our results with those obtained by a common HPLC method has also been carried out. (C) 2009 Elsevier Ltd. All rights reserved.