Study on Mechanism and Application of High Concentrations of Nitrite-Induced Specific Color Fading

Abstract

Nitrite and edible salt are easy to confuse for their similar appearance and taste, thus possibly causing nitrite poisoning. Therefore, it is particularly crucial to figure out how to screen high concentrations of nitrite, how to discriminate NaNO₂ and NaCl, and how to accurately quantify high concentrations of nitrite. In this study, the phenomenon of high concentrations of nitrite fading to orange-yellow color in colorimetric solution of naphthalene ethylenediamine hydrochloride was studied and accurately quantified by dilution colorimetry. It is to prevent false negative detection while NaCl presented no such phenomenon. Through spectrophotometry, high-performance liquid chromatography, and liquid mass spectrometry, we discovered that the principle of high concentrations of nitrite fading to orange-yellow after colorimetry was that high concentrations of nitrite nitrosated azo compounds and naphthalene ethylenediamine hydrochloride in hydrochloric acid medium. This principle can make the solution appear orange-yellow while had almost no matrix interference and this demonstrates no difference in food and water. We thus argue that this principle can be used for the screening of high concentrations of nitrite, and discriminating NaNO₂ and NaCl to prevent poisoning events caused by misuses. In this sense, we believe the principle in question has a high applying value and is worth promoting. It can be made into a commercial hydrochloric acid acidified naphthylethylenediamine hydrochloride solution for further commercialized applications.