Preparation of Sample Solution for Determination of Nitrate and Nitrite in Various Foods by Colorimetry and Ion Chromatography

A method for preparation of sample solution for determination of nitrate and nitrite in vegetables, beef and their processed foods by colorimetry and suppressed ion chromatography (IC) with UV detection has been developed. Nitrate and nitrite were simultaneously extracted from foods with sodium borate solution at 80°, then the extracts were cooled and filtered through an ultrafilter (Molcut II). Nitrite was determined in the filtrate by colorimetry, and nitrate by IC. In the case of determination of nitrate in foods containing more than 3% sodium chloride, the salt was eliminated from the extracts by using an On Guard-Ag cartridge. The recoveries of nitrate were 90.0-102.0% from foods fortified at 5-1, 000μg/g, and those of nitrite were 84.2-101.0% from foods fortified at 5-50μg/g.