Speciation of nitrite, nitrate and p-nitrophenol by photochemical vapor generation of NO using High-Resolution Continuum Source Molecular Absorption Spectrometry

Abstract

This paper presents a new speciation method of n-compounds in food samples using the technique of High-Resolution Continuum Source Molecular Absorption Spectrometry (HR-CS MAS). The nitrite ion was determined in a quartz cell of the HR-CS MAS by generating NO steam. Speciation methods of nitrite and nitrate were studied, using the reduction of nitrate to nitrite. The most efficient alternative was the irradiation of ultraviolet light (UV) in the samples containing nitrate in an ammonium bufferand EDTA. Therefore,the nitrate concentration in the samples, using the reduction process to nitrite,was added to the previous nitrite concentration and was specified by subtracting the initial concentration to the final one. The p-nitrophenol was determined by its degradation throughUV in the presence of H2O2, generating, among other products, nitrite, which was determined through the reduction of nitrite to NO steam. After that, samples of natural water and canned foods were analyzed. The R2, LOD (mg L−1), LOQ (mg L−1) and m0 values were, respectively 0.990; 0.047,0.16 and 0.25 μg, for nitrate; 0.990; 0.090 and 0.30 and 0.52 μg, for nitrate, and 0.996; 0.034, 0.11 and 0.29 μg, for p-nitrophenol.