Cu2+和Zn2+对模拟胃液中NDMA形成的影响

【目的】在模拟胃液条件下研究重金属Cu~(2+)和Zn~(2+)对内源致癌性N-二甲基亚硝胺(NDMA)形成的影响,并进一步探讨其作用机理。【方法】分别用气相色谱-质谱联用法(GC-MS)和离子色谱法(IC)来测定NDMA、二甲胺(DMA)和亚硝酸根(NO_2~-)含量。【结果】在模拟胃液条件下,Cu~(2+)和Zn~(2+)浓度高于50mg/L时,可以促进NDMA的形成,且当浓度由50mg/L增大到200mg/L时,Cu~(2+)促进率由1.16%增大到94.56%,Zn~(2+)促进率由21.32%增大到45.86%。在重金属浓度为符合或接近符合水质基准值1.0mg/L时,Cu~(2+)和Zn~(2+)对NDMA的形成也分别有16.88%和13.42%的促进率;而当重金属浓度为10mg/L时,两种离子却均抑制NDMA的形成。机理研究表明Cu~(2+)、Zn~(2+)促进NDMA的形成主要是由于其与DMA发生相互作用,进而导致NDMA形成。【结论】高浓度的Cu~(2+)和Zn~(2+)通过与DMA相互作用,形成活性中间体从而促进NDMA的生成。

Studies on the Effect of Cu2+ and Zn2+ on Carcinogenic NDMA Formation in Simulated Gastric Fluid

Objective] The aim of this study was to investigate the effect of heavy metal irons Cu²⁺ and Zn²⁺ on the formation of N-nitrosodimethylamine (NDMA)in simulated gastric fluid (SGF)and further explore its mechanism.Methods] The concentrations of NDMA and dimethylamine (DMA), nitrite (NO₂^-)were determined by gas chromatography-mass spectrometry (GC-MS)and ion chromatography (IC), respectively.Results] Cu²⁺ and Zn²⁺ could promote the formation of NDMA when the concentrations of Cu²⁺ and Zn²⁺ were higher than 50mg/L in simulated gastric fluid (SGF).Meanwhile, the promotion rates were increased from 1.16%to 94.56% and 21.32% to 45.86% for Cu²⁺ and Zn²⁺, respectively, with their concentrations increasing from 50mg/L to 200mg/L.It is noteworthy that very low concentration of Cu²⁺ and Zn²⁺ at 1.0mg/L, which already or almost met their guideline values in drinking water, could still enhance NDMA formation with the promotion rates of 16.88% and 13.42%, respectively.Interestingly, both Cu²⁺ and Zn²⁺ could inhibit NDMA formation when their concentration was 10 mg/L.Mechanism research showed that the promotion of the NDMA was mainly due to the interaction between the heavy metal ions and DMA.Conclusion] Heavy metal ions Cu²⁺ and Zn²⁺ at relatively high concentrations can both promote NDMA formation in SGF through interacting with DMA.