Simultaneous determination of nitrite and nitrate in meat products and vegetables by capillary electrophoresis

A capillary electrophoresis method for the simultaneous analysis of nitrite and nitrate in meat products and vegetables using direct UV detection is reported. The method is based on the separation of two anions in a capillary coated with polyethyleneimine (PEI). Since PEI is a cationic polymer, the electroosmotic flow is reversed over a wide pH range and the fast separation of anions is achieved without the addition of any electroosmotic modifier to the separation buffer. The detection limit of the method is sufficiently low for food products. Good reproducibility and recovery results were obtained using thiocyanate as internal standard.