Rapid and sensitive determination of nitrite in foods and biological materials by flow injection or high-performance liquid chromatography with chemiluminescence detection.

A method is described for the determination of nitrite that is based on reduction of nitrite with potassium iodide followed by chemiluminescence detection of the liberated NO using a thermal energy analyzer. The method worked well both in the flow injection mode and upon interfacing with a reversed-phase high-performance liquid chromatography system. Limited data available indicated a good agreement between results obtained by the chemiluminescence method and those obtained by using a well established colorimetric procedure when they were applied for the determination of nitrite in a number of cured meats, human saliva, and baby foods. The chemiluminescence method is, however, much superior to the colorimetric one in its speed, versatility, as well as sensitivity (200 times more), and requires only a minimum of sample preparation. The detection limit of the new method is about 0.1 ng NaNO2 per injection or 5 micrograms/kg in cured meats and other substrates analyzed.