The determination of nitrite and nitrate in foods by capillary ion electrophoresis

Capillary ion electrophoresis (CIE) has been used to determine the nitrite and nitrate content of a range of foods. The samples tested were cheese, cabbage puree, fruit juice, water and a variety of meat products. A 75 cm × 75 μm i.d. fused silica capillary column was used, with a simple OFM Anion-BT/sodium chloride electrolyte. The operating voltage was −20kV, the temperature 28 °C and the detection wavelength 210 nm. Significant amounts of nitrate were found in some of the meat products, its source being the chemicals used in the curing process. Initial work with iodide and tungstate as internal standard was discontinued in favour of thiocyanate, owing to poor resolution of chloride and iodide, and relatively poor peak shape and inconsistent peak areas for tungstate. Good recoveries of nitrite and nitrate were obtained with thiocyanate as internal standard. The data gathered indicate that the method is suitable for determining nitrite and nitrate in a variety of foods.