水産食品におけるニトロソジメチルアミン（ＮＤＭＡ）の生成 ＩＩ アスコルビン酸存在下のニトロソジメチルアミン生成に関する再検討

Abstract

The author and a co-worker had reported the accelerative effect of ascorbate on the formation of N-nitrosodimethylamine (NDMA) in a buffer solution containing NaNO2 and dimethylamine (DMA) at pH 6. The author later questioned whether or not the usual procedure of extracting NDMA from the test solution could stop the additional nitrosation of DMA. Therefore, a newmethod for removal of DMA from the test solution with the aid of cation exchange resin prior to extraction was devised, to completely stop the nitrosation reactions. The yield of NDMA in the test solution was measured using this method (resin method) and the usual methods performed with or without addition of NaOH to the solution before extraction with CH2Cl2. It was found that very large values due to the artifactual yield of NDMA during the extraction process were obtained by the usual method in the case of a solution containing ascorbate at pH 6. The resin method also revealed that ascorbate usually showed an inhibitive effect on the formation of NDMA in experiments at pH 6, and, the higher the concentration of ascorbate or the lower the reaction temperature, the more the degree of inhibition. Thus, the previous information about the “accerelative effect” of ascorbate on the formation of NDMA at pH 6 was corrected by the above results. Ammonium sulfamate, recently used by several workers as a quenching reagent for nitrosation reactions, was also tested in this study and compared with the resin method. The values of NDMA yield obtained by the method using the reagent were slightly higher than those measured by means of the resin method in the case of the test solution containing ascorbate.