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New Colorimetric Method for the Determination of the Nitrate and Nitrite Content of Baby Foods
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1965
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NutritionBaby FoodsEngineeringFood AnalysisAgricultural EconomicsFood ContaminantFood ChemistryAnalytical ChemistryFood SciencesNew Colorimetric MethodNitrite ContentHealth SciencesFood CompositionFood QualityMicronutrientsFood PreservativesCadmium ColumnFood SafetyEnvironmental EngineeringInfant NutritionColorimetryNitrite Passes
Abstract A new method for the determination of nitrite and nitrate in foods will accurately determine concentrations as low as 1 ppm. 1-Naphthylamine is diazotized by nitrite and coupled with excess amine to give 4-(lnaphthylazo)-l-naphthylamine. The compound is extracted into CHCI3, the extract is acidified with methanol-hydrochloric acid, and absorbance is measured at 555 mµ. Nitrate is quantitatively reduced by passage through a cadmium column and determined as nitrite; nitrite passes through the column unaltered. Therefore, in samples containing both forms of nitrogen, nitrate is determined by difference. The method was applied to 194 samples of baby foods. Spinach, beets, wax beans, squash, “garden vegetables,” green beans, carrots, and “mixed vegetables” were found to contain, on the average, more than 20 ppm nitrate nitrogen.