| N-nitrosodimethylamine (NDMA), as one of N-nitrososamines, has arousedwidespread concern due to its strong carcinogenic, mutagenic and teratogenic. Theinvestigation of the effect of related substances on the formation of NDMA, inhibitionor catalysis, has become hot in recent years. In this paper, the detection platform ofNDMA was first established and then the investigation on the effect of naturalproducts and heavy metal ions on the NDMA formation was carried out. Three partswas included as following.1. The establishment of NDMA detection method and assessment platform of theeffect of related substance on NDMA formation.A gas chromatography mass spectrometry (GC/MS) method was establised todetect NDMA in water. Various parameters of GC/MS for detection of NDMA wereoptimized. The solid phase extraction column (SPE) was used as pretreatment method,which was filled with coconut shell activated carbon by ourselves. The recovery rateof our SPE column can reach98.6%and the relative error is only2.7%as well as itcan be used five times.A platform for assessing the effects of related substances on the formation ofNDMA was established, and the conditions for the platform were optimized. Theoptimized reaction conditions including reaction pH being3.4, the reaction volumebeing10mL, the reaction temperature being37oC, concentrations of DMA andsodium nitrite being15and25mM, respectively, and reaction time being2h.2. Investigation of the inhibition of natural products on NDMA formationThe investigation of effects of nine natural products, i.e., Rosmarinus officinalis,Ginkgo biloba, Rhizoma corydalis, Echinacea purpurea, Cinnamomum cassia,Hippophae rhamnoides linn seed, Desmodium styracifolium, Rhizoma anemarrhenae,and Pinus massoniana lamb, on NDMA formation was performed. The resultsshowed that all nine natural products except for pine bark have significant inhibitingeffects on NDMA formation with the inhibition rate above70%. Especially, theinhibition rates of Desmodium styracifolium, Ginkgo biloba, and Rosmarinusofficinalis are above90%.The effects of Desmodium styracifolium, Ginkgo biloba, and Rosmarinusofficinalis on NDMA formation was investigated at different concentrations. We found that the three natural products all have significant inhibitory effect on NDMAformation with50%inhibitory rate at the concentration of0.1mg/L. The investigationresults for empolder of natural product inhibitors provide a theoretical basis, whichhas positive guiding significance for human health maintenance at the same time.3. Investigation of the effects of cadmium, lead, and mercury ions on NDMAformationUnder acidic conditions, cadmium (Cd), lead (Pb), and mercury (Hg) ions wereall found to promot the formation of NDMA with the promotion rates being19.22%,29.83%, and3.91%, respectively, when the concentration of three heavy metal ions is0.01mg/L which meets or almost meets the water quality baseline value. With theincreasement of the concentrations of heavy metal ions (except Pb ion), the formationof NDMA increased significantly and promotion rates reaches60.39%,24.71%, and35.93%, respectively, when the concentration of heavy metal ions of1mg/L. Underdifferent concentrations, lead has different changes of promotion rate with those ofcadmium and mercury ions. It suggests that in comparion with cadmium and mercuryions, the lead ion has different promotion mechanism on the formation of NDMA.The findings can contribute to the understanding of the mechanism of heavy metalpollution of the environment, which provide a strong reference to effective control thethreshold of environmental factors. |
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