考古发掘出土的遗物中, 有机残留物大部分是以附着在器物上, 或者是遗址表面而存在的, 由于没有固定形状, 或量少而难以发现, 且不易保存, 因此常常被忽视。 但是这类有机物作为古代人类生活生产资料, 包含重要的历史信息, 具有珍贵价值。 通过遗址中发现的器物或者有机残留物, 可以决定器物甚至是遗址的用途, 古代照明燃料就属于这类有机残留物。 中国古代多使用动物油、 植物油、 蜡等作为照明燃料, 对植物油和蜡都有一定研究, 但对于动物油种类的分析仅停留在区分反刍动物与非反刍动物。 引入热裂解气相色谱质谱技术(THM-Py-GC/MS)研究有机残留物, 使用600 ℃裂解温度经过12 s裂解时间, 可以将甘油三酯与老化过程中由于失去酰基逐步形成的双酰基甘油、 单酰基甘油等完全裂解成甘油与脂肪酸, 通过计算脂肪酸相对含量, 可以分析不同动物油具有的特征。 同时用高温裂解代替了传统酸化提纯样品的预处理方法, 能最大程度的保留样品中的各组分。 加入过量的四甲基氢氧化铵, 可将样品中脂肪酸与醇等量转化为对应的酯和醚, 在气相色谱初始50 ℃保持5 min, 然后以10 ℃·min^-1升至280 ℃保持10 min的条件下, 将甲基化的样品组分分离, 质谱以1∶100的分流比进行测定。 对内蒙古伊和淖尔墓地出土铁灯内的残留物进行了分析, 结果显示, 灯内残留物样品中主要成分是C7—C22连续碳原子的脂肪酸, 含量较高的饱和脂肪酸有十四烷酸、 十五烷酸、 十六烷酸、 十七烷酸、 十八烷酸等。 对比老化前与老化后猪油、 牛油、 羊油等动物脂肪参考样品所含主要成分与相对含量, 老化后的羊油中的奇数碳饱和脂肪酸含量明显高于其他两种动物油, 并且这一特征也体现在考古样品中, 结合以往文献中动物油成分的研究结果, 可以判断出残留物中所含动物油的确切种类属羊油。 此外样品中包含的碳氢化合物与醇属于蜡的成分, 根据脂肪酸及醇的相对含量可以判断为蜂蜡。 热裂解气相色谱质谱技术(THM-Py-GC/MS), 为出土有机残留物, 特别是动物脂肪种类的的分析研究, 提供了更加高效、 便捷的方法。 并且, 对混合有机残留物种类的鉴别也做出了有益的尝试。

In the unearthed relics, most of the organic residues are attached to the objects or the surface of archaeological sites. Organic residues are often neglected in previous studies, because they have no definite shape, sometimes the amount of them is small and difficult to be found and preserved. However, as materials for ancient human life, this kind of organic residues contain important historical information and have cherished value. Even through the organic residues found in objects or sites, it can determine the use of objects and even sites. Ancient illuminating fuel belongs to such kind of organic residues. Animal tallow, vegetable oil and wax were used in ancient China. Vegetable oil and wax have been studied in the past, but the research of animal tallow only stays in distinguishing ruminants from non-ruminants. In this paper, pyrolysis gas chromatography-mass spectrometry (Py-GC/MS) was introduced to study organic residues. Triglyceride and production in aging process could be completely decomposed into glycerol and fatty acid due to the loss of acyl group by pyrolysis temperature of 600 ℃ and pyrolysis time of 12 s. By calculating the relative content of fatty acid, the characteristics of different animal oils could be analyzed. At the same time, high temperature pyrolysis replaces the traditional pretreatment method of acidizing and purifying samples, which can retain the components of samples to the greatest extent. With the addition of excessive tetramethylammonium hydroxide, the fatty acids and alcohols in the sample can be converted into corresponding esters and ethers. The methylated sample can be separated at the initial 50 ℃ of gas chromatography for 5 minutes, then elevated to 280 ℃ for 10 minutes. The methylated sample components can be determined by mass spectrometry at a split ratio of 1∶100. The residual illuminating fuel from an iron lamp, which was excavated in a tomb from Yihenaoer, Inner Mongolia, were analyzed. According to the results, the main components of residues were fatty acids with continuous number of carbon atoms ranging from 7 to 22, in which relative content of tetradecanoic acid, pentadecanoic acid, hexadecenoic acid, heptadecanoic acid and octadecanoic acid were higher. Compared with the compounds of lard, beef tallow, and mutton tallow (three main kinds of animal tallows used as illuminating fuels), the contents of odd number of carbon atoms of fatty acids in mutton tallow were significantly more than the other two kinds of animal tallous. And this feature was also verified in archaeological sample. By combination with the other researchers’ results, the exact type of animal tallow contained in residues should be mutton tallow. Moreover, the hydrocarbons and alcohols contained in the archaeological sample were identified as beeswax according to the relative contents of fatty acids and alcohols. Thermally assisted hydrolysis-methylation pyrolysis-gas chromatography-mass spectrometry (THM-Py-GC/MS) provides a new method for the analysis of organic residues, especially animal tallous. In addition, a useful attempt has been made to identify the species of mixed organic residues.