Ozonolysis of uric acid at the air/water interface
Ozonolysis of uric acid at the air/water interface
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DOI：
10.1021/jp712010k
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发表时间：
2008-04-10
影响因子：
3.3
通讯作者：
Colussi, A. J.
中科院分区：
文献类型：
--
作者：
Enami, Shinichi;Hoffmann, M. R.;Colussi, A. J.
尿酸（UA）的环氧化物，过氧化物，臭氧化物的水UA微滴中产生的物质暴露于O-3（g）的检测通过在线质谱在类似1毫秒。UA转换是独立的，其初始浓度低于类似0.1 mM，并不受影响，通过添加过量的H2 O2或叔丁醇。从pH 4到7，UA反应性增加了约380倍，这与本体水中UA + O-3（aq）反应所报告的与pH无关的速率不同。在pH值接近7时，UA和抗坏血酸（AH（2））微滴以相似的速率与O-3（g）反应，尽管UA对本体水中O-3（aq）的反应性比AH（2）高40倍。在混合UA（aq）和O-3（aq）溶液时，仅形成UA环氧化物和痕量的UA过氧化物。我们推断，气-液臭氧分解的UA收益在一个界面的水介质相当不同的散装水。因此，UA，肺上皮衬里液的一种成分，将大气中的O-3（g）清除为有害程度较低的物质（类似于AH（2）），在pH值低于5时失去活性。对流层臭氧和酸性颗粒物之间的协同健康效应的这些发现的潜在影响进行了简要分析。
Uric acid (UA) epoxide, peroxide, and ozonide species produced in aqueous UA microdroplets exposed to O-3(g) are detected by online mass spectrometry within similar to 1 ms. UA conversions are independent of its initial concentration below similar to 0.1 mM and are unaffected by addition of excess H2O2 or t-butanol. UA reactivity increases similar to 380 times from pH 4 to 7, which is at variance with the pH-independent rates reported for the UA + O-3(aq) reaction in bulk water. At pH similar to 7, UA and ascorbic acid (AH(2)) microdroplets react with O-3(g) at similar rates, although UA is similar to 40 times more reactive than AH(2) toward O-3(aq) in bulk water. Only the UA epoxide, plus traces of UA peroxide, are formed upon mixing UA(aq) and O-3(aq) solutions. We infer that the gas-liquid ozonolysis of UA proceeds in an interfacial aqueous medium quite distinct from bulk water. Thus, UA, a component of the pulmonary epithelial lining fluid that scavenges atmospheric O-3(g) into less deleterious species (similar to AH(2)), is rendered inactive below pH similar to 5. The potential implications of these findings on synergistic health effects between tropospheric ozone and acidic particulates are briefly analyzed.