煤中有机质可溶组分分子特征的聚类分析

Cluster Analysis of Molecular Characteristics for Soluble Organic Matter in Coals

煤中有机质组成与分布的认知是煤精细化工产业发展的基础,高分辨率质谱可以获得更丰富的煤中有机质的分子信息,基于化学计量学的数据统计方法可以实现对大量数据的可视化分析,更为全面地揭示数据间的关系。本研究对6种我国典型产煤区的中低阶煤样进行二级分级萃取(正己烷和甲醇),并采用气相色谱-质谱联用仪(GC/MS)和电喷雾-飞行时间质谱仪(ESI-TOF/MS)对12组萃取物进行分析,探究煤可溶物中分子的组成与分布特征。基于R语言的统计学方法对12组萃取物数据进行系统聚类分析,聚类准确率为100%。在12组萃取物中,基于聚类分析的树图显示,正己烷对于烷烃和芳烃有较好的萃取效果,甲醇对含氧化合物具有较好的富集作用。基于聚类分析的热图显示,GC/MS分析得到的芳烃相对含量最高,且主要为多环芳烃类化合物; ESI-TOF/MS检测到ON化合物的相对含量最高,这与ESI正模式易电离含氮的碱性有机化合物有关。

The recognition of the composition and distribution of organic matter in coal is the basis for the development of coal-based fine chemical industry.High-resolution mass spectrometry(MS)can obtain more abundant molecular information of organic matter in coal compared to routine ones.At the meantime,the large amount of data generated by high-resolution MS brings a challenge to the efficient mining of spectral information.Statistical methods can quickly complete the analysis of a large amount of data,realize data visualization and meet the needs of comprehensive scientific researches.In this study,a two-stage fractional extraction(n-hexane and methanol)was carried out on six coal samples from typical coal mines in China to obtain 12 extracts.Gas chromatography/mass spectrometry(GC/MS)and electrospray-time-of-flight mass spectrometry(ESI-TOF MS)were used to analyze the 12 extracts to explore the molecular characteristics in composition and distribution.Based on the programs tun by R language,systematic cluster analysis of MS data from the 12 extracts could quickly obtain the relative content and distribution of compounds.The clustering results were completely consistent with the actual results.It was found that n-hexane had better extraction effects on alkanes and aromatics,and methanol had a better extraction effect on oxygenates.From GC/MS data,the relative content of aromatic hydrocarbons was the highest,mainly consisting of polycyclic aromatic hydrocarbons.The relative content of ON compounds was the highest in the data from ESI-TOF/MS,because ESI at positive mode inclines to ionize basic nitrogen-containing organic compounds.In the n-hexane extract,ONS-containing compounds had the highest content.For methanol extract,ON-containing compounds had the highest content,which was related to the cleavage of C-S bond.