Studies on Nitrosamines in Foods (X)

Relation of Alkalinity to Recovery in the Determination of Secondary Amines

Abstract

In the previous paper, the colorimetric determination method of dimethylamine in foods using alkali-steam distillation was reported. Recently, however, a question was proposed agamst the steam distillation with 10N sodium hydroxide solution, because there were some possibilities of formation of dimethylamine from monomethylamine, trimethylamine or trimethylamine oxide which were contained in foods.
Comparing the color intensity of dimethylamine, monomethylamine, trimethylamine and trimethylamine oxide after steam distillation with sodium hydroxide, color intensity of monomethylamine, trimethylamine and trimethylamine oxide were much less than that of dimethylamine, and in the case of dimethylamine, its recovery by the same procedure was between 98-102%. And also, by the addition of 500ppm of trimethylamine oxide into the fish meat slurry followed by alkali-steam distillation, the changes of the values did not exceed 5% compared with the control. From the results of the experiments, we could not find any disturbance in the process of the determination.
A proposed method in which magnesium oxide is used instead of 10N sodium hydroxide solution was also tested, but the recovery of dimethylamine in the proposed method was below 10%.