Determination of nitrate in dried foods by gas chromatography-thermal energy analyzer

The method described for determining NO3- in dried foods is based on extraction of NO3- from the sample with subsequent nitration of benzene. The nitrobenzene is extracted with ethyl acetate, analyzed by using a gas chromatograph-thermal energy analyzer (GC-TEA), and quantitated against a nitrobenzene standard. Sensitivity is 100-200 micrograms/kg. Coefficients of variation for analyses of dried foods were 3-13%. Recovery of NO3- from nonfat dry milk spiked at 10 mg/kg averaged 100%.