The method consists in extracting of a test portion with hot water, precipitating of proteins and filtrating. Reduction of the extracted nitrates into nitrites by metallic cadmium. Formation of a red colouration by adding of sulfanilamide and nphthyl ethylenediamine hydrochloride and photometric measurement at a wavelength of 538 nm.
PUBLISHED SRPS ISO 3091:1999 90.93
Standard confirmed Dec 31, 2012