依次用CS2、乙酸乙酯、甲醇和丙酮萃取内蒙古霍林郭勒褐煤,得到各级萃取物.采用配有大气压光电离源(APPI)的飞行时间质谱仪对所得萃取物进行分析.选择甲苯和1,4-二氟苯作为APPI电离条件下的助离子化剂.结果表明,1,4-二氟苯和甲苯都表现出较好的助离子化效果,得到更多煤的可溶组分的分子信息.其中甲苯对离子信号强度的提升作用更为明显.在煤的各级萃取物中发现了较多的二聚体现象,可能是分子间缔合形成的分子簇,这间接证明了煤体系内存在分子间缔合交联现象.并且发现缔合分子均含有杂原子.在3种离子化条件下,煤萃取物的分子量分布区间差异不大: 60%的萃取物分子量在200~500 Da之间,约10%的萃取物分子量>500 Da.大气压光电离质谱离子化法结合1,4-二氟苯和甲苯这两种助离子化剂均能很好地分析煤中分子量较大(> 500 Da)的弱极性或非极性化合物.%Huolinguole lignite was sequentially extracted with carbon disulfide, ethyl acetate, methanol and acetone.All of the extracts were analyzed using a time-of-flight mass spectrometry (TOF-MS) equipped with an atmospheric pressure photoionization (APPI) ion source.Toluene or 1,4-difluorobenzene was chosen as dopant for APPI.The results indicated that both dopants could well ionize compounds which could not be ionized by APPI without dopant.Toluene induced higher ionization efficiency than 1,4-difluorobenzene.Some compounds in the extracts were identified as dimers, which might be formed via molecular association.Heteroatoms were identified in all of the associated molecules.Molecular weight distributions under three APPI ionization modes were similar.Compounds with molecular weight from 200 to 500 Da occupied 60% of all the products and around 10% of the products had molecular weight over 500 Da.
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