Abstract
Cow milk, human milk and water in several areas in Hokkaido were analyzed for nitratenitrogen (NO3-N) by the cadmium column method, nitrite-nitrogen (NO2-N) by the diazocoupling reaction method and dimethylaminenitrogen (DMA-N) by the Cu-dithiocarbamete method.
Average content of NO3-N in 380 samples of cow milk was 0.1ppm and NO2-N was undetected (under the limit of 0.01ppm), but high NO3-N levels (0.05-9.57ppm) and NO2-N levels (0.01-0.47ppm) were found in human milk especially in colostrum. The ground water contained higher amount of NO3-N and NO2-N than the city water.
The DMA-N contents in cow and human milk were of trace level.
