电喷雾离子源傅立叶变换离子回旋共振质谱分析IHSS Nordic湖富里酸的分子结构

Characterization of IHSS Nordic lake fulvic acid by electrospray ionization fourier transform ion cyclotron resonance mass spectrometry

基于电喷雾离子源傅立叶变换离子回旋共振质谱(ESI FT-ICR MS)技术,分析了IHSS Nordic湖富里酸参考样品的分子组成。结果表明:Nordic湖富里酸主要是由CHO类物质组成的,含S物质来源于微生物的作用,含N物质来源于微生物作用或陆源输入;木质素类组分是Nordic湖富里酸占比最大的组分,其来源可能是水体植物降解时释放的水溶性木质素;AImod值表明CHON类物质的芳香性结构最强;在CHO类物质中,DBEaverage随着氧原子的增加表现出先减后增的趋势,两部分的相关性指数r^2分别为0. 7456和0. 9888,且随着氧原子的增加,高不饱和度的分子占的比例也越来越大,说明低氧原子数的分子含有较多的羟基和支链结构,高氧原子数的分子有较多的羧基和芳香结构。实验结果拓宽了对富里酸分子结构的认识,有助于进一步了解与污染物质的结合机理。

It is necessary to understand the molecule composition of fulvic acid, which plays a significant effect on transport and bioavailability of pollutants in environment. We present the extensive characterization of IHSS Nordic Lake fulvic acid reference sample by electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry ( ESI FT-ICR MS). The results show the dominant category is CHO compounds. N, S-containing compounds are produced by microbial activities, and N-containing compounds may also in put by terrigenous. The major part of Nordic Lake fulvic acid is lignin, which mainly originates from the release of water-soluble lignin by biodegradation of plants. CHON compounds have higher degree of aromatic structure according to AImod value. The DBEaverage increases firstly and then decreases with the number of oxygen increasing in CHO compounds, the correlation values of r^2 are 0. 7456 and 0. 9888 , respectively. It is clear that ratio of high DBE value increases as the number of oxygen increases. All these indicate the molecules with lower oxygen atoms are likely to contain more hydroxyl groups and branched chain structures, while carboxyl groups and aromatic structures may exist in molecules with more oxygen atoms. The work has broaden the understanding of the molecular structure of fulvic acid , contributing to the further study of the interaction mechanism with the pollutants.