Specific Determination of Nitrate and Nitrite of Chicken Egg by Gas-Liquid Chromatography with Special Reference to the Turnover of These Anions in Laying Hens

Abstract

Nitrate and nitrite were successfully extracted from deproteinized chicken egg with aqueous solution, and analyzed by gasliquid chromatography with an electron capture detector without further cleaning. The distribution of these anions in 50 egg samples was the logarithmic normal distribution in each case, that is, N (2.796 (=0.063ppm), 0.295) and p {0.052ppm ?? μ ?? 0.076ppm}=0.95 for nitrate-N, and N (2.470 (=0.030ppm), 0.227) and p {0.026ppm ?? μ ?? 0.034ppm}=0.95 for nitrite-N. When the chickens were fed with a commercial diet containing elevated levels (1, 000 or 5, 000ppm) of nitrate- or nitrite-N, the concentration of these anions in their eggs markedly increased and proceeded to the steady state within 2 or 3 days, where the level was proportional to that of anions added to the diet. After withdrawing the excess of anions from the diet, the concentrations of anions in the eggs decreased exponentially, where the rate constants for nitrate and nitrite were about 0.6 day^-1 and 1.0 day^-1, respectively. In the series of experiments, it was assumed that the reactions NO₃^-→NO₂^- and NO₂^-NO₃^- proceed simultaneously in the body of chickens.