傅里叶变换离子回旋共振质谱分子表征^(15)N同位素标记羟胺衍生化天然有机质  

Molecular characterization of 15N-labelled hydroxylamine-derivatized natural organic matter by FTICR-MS

作　　者：曹冬[1] 耿方兰[1] 饶子渔 康跃惠[1] CAO Dong;GENG Fanglan;RAO Ziyu;KANG Yuehui(State Key Laboratory of Environmental Chemistry and Ecotoxicology,Research Center for Eco-Environmental Science,Chinese Academy of Sciences,Beijing,100085,China)

机构地区：[1]中国科学院生态环境研究中心,环境化学与生态毒理学国家重点实验室,北京100085

出　　处：《环境化学》2023年第4期1118-1127,共10页Environmental Chemistry

基　　金：国家自然科学基金(重点项目22036007)资助.

摘　　要：羟胺化合物是地球氮循环过程中的重要中间产物.天然有机质(NOM)作为环境中普遍存在的复杂有机混合物,对羟胺的环境转化有重要影响.本研究采用傅里叶变换离子回旋共振质谱(FTICRMS)在分子层面表征羟胺与NOM的相互作用产物,采用^(15)N同位素标记羟胺作为反应物以排除NOM本身存在的化合物的质谱峰干扰,特异性识别^(15)N同位素标记羟胺衍生化NOM的质谱信号;同时考察了反应时间对NOM与羟胺反应活性的影响.结果表明,NOM与过量^(15)N同位素标记羟胺在室温条件反应下10 h,可以鉴定到2137个^(15)N同位素标记羟胺衍生化NOM产物分子式,其中包括,1个^(15)N同位素标记羟胺分子与1个仅含C、H、O元素的NOM分子反应形成的产物分子式1346个(CHO^(15)N_(1),约占产物分子式总数63%),两个^(15)N同位素标记羟胺分子与一个仅含C、H、O元素的NOM分子反应形成的产物分子式194个(CHO^(15)N_(2),约占产物分子式总数9%),一个^(15)N同位素标记羟胺分子与一个仅含C、H、O和一个S元素的NOM分子反应形成的产物分子式376个(CHOS1^(15)N_(1),约占产物分子式总数18%),一个^(15)N同位素标记羟胺分子与一个仅含C、H、O和一个N元素的NOM分子反应形成的产物分子式221个(CHON_(1)^(15)N_(1),约占产物分子式总数10%).这些羟胺衍生化NOM产物主要属于维管植物源多酚类和高不饱和酚类化合物,86%以上的产物很可能通过羟胺与NOM分子所含的羰基基团发生肟化反应形成.CHO^(15)N_(1)类产物的形成具有高度的时间依赖性,高氧化高饱和度的NOM化合物需要较长的反应时间才能形成羟胺衍生化NOM产物,表明此类化合物与羟胺的反应活性较弱;而低氧化高不饱和度的NOM化合物仅需要较短的时间便能形成羟胺衍生化产物,且随着反应时间延长,其中的部分化合物可以进一步生成多肟化产物或不稳定的其他产物,此结果表明这类NOM化合物对羟胺�Hydroxylamine is a crucial intermediate in the natural nitrogen cycle.Natural organic matter(NOM),as a very complicated heterogeneous mixture widely existing in the environment,may affect the transformation processes of hydroxylamine.Here,Fourier transform ion cyclotron resonance mass spectrometry(FTICR-MS)is used for molecular characterization of hydroxylamine derivatized-NOM.^(15)N-labelled hydroxylamine is applied to specifically discriminate ^(15)N-labelled hydroxylamine derivatized-NOM from other interferences original existing in NOM.The effect of reaction time on the reactivity of NOM to hydroxylamine is investigated.A total of 2137 molecular formulas of the derivatives are obtained including CHO^(15)N_(1)(1346,63%),CHO^(15)N_(2)(194,9%),CHOS1^(15)N_(1)(376,18%)and CHON_(1)^(15)N_(1)(221,10%).The ^(15)N-labelled hydroxylamine derivatizedNOM are mainly assigned to vascular plant-derived polyphenols and highly unsaturated and phenolic compounds.More than 86%of the derivatives appear to be formed by oximation reaction.The generation of CHO^(15)N_(1) derivatives is highly time dependent.More oxidized and saturated NOM CHO compounds need long time to form the hydroxylamine derivatives,indicating they appear to be less liable to react with hydroxylamine,while less oxidized and more unsaturated NOM CHO compounds could form the hydroxylamine derivatives in short time,and some of them even could generate multi-oximed products or other unstable products within longer time,which suggests they may have high reactivities to hydroxylamine.This is the first report on the comprehensively molecular characterization of the hydroxylamine derivatized-NOM by FTICR-MS and can provide new insight into the research on migration and transformation mechanism of hydroxylamine in the nitrogen cycle.

关 键 词：15N 同位素标记羟胺 傅里叶变换离子回旋共振质谱 天然有机质 羟胺衍生化天然有机质 

分 类 号：P595[天文地球—地球化学] X142[天文地球—地质学]