Oras Ester, Vahur Signe, Isaksson Sven, Kaljurand Ivari, Leito Ivo
Institute of History and Archaeology, Faculty of Arts and Humanities, University of Tartu, Jakobi 2, 51014, Tartu, Estonia.
Institute of Chemistry, Faculty of Science and Technology, University of Tartu, Ravila 14A, 50411, Tartu, Estonia.
J Mass Spectrom. 2017 Oct;52(10):689-700. doi: 10.1002/jms.3974.
Soft-ionization methods are currently at the forefront of developing novel methods for analysing degraded archaeological organic residues. Here, we present little-used soft ionization method of matrix assisted laser desorption/ionization-Fourier transform-ion cyclotron resonance-mass spectrometry (MALDI-FT-ICR-MS) for the identification of archaeological lipid residues. It is a high-resolution and sensitive method with low limits of detection capable of identifying lipid compounds in small concentrations, thus providing a highly potential new technique for the analysis of degraded lipid components. A thorough methodology development for analysing cooked and degraded food remains from ceramic vessels was carried out, and the most efficient sample preparation protocol is described. The identified components, also controlled by independent parallel analysis by gas chromatography-mass spectrometry (GC-MS) and gas chromatography-combustion-isotope ratio mass spectrometry (GC-C-IRMS), demonstrate its capability of identifying very different food residues including dairy, adipose fats as well as lipids of aquatic origin. The results obtained from experimentally cooked and original archaeological samples prove the suitability of MALDI-FT-ICR-MS for analysing archaeological organic residues. Sample preparation protocol and identification of compounds provide future reference for analysing various aged and degraded lipid residues in different organic and mineral matrices.
软电离方法目前处于开发分析降解的考古有机残留物新方法的前沿。在此，我们介绍一种很少使用的软电离方法——基质辅助激光解吸/电离-傅里叶变换-离子回旋共振质谱法（MALDI-FT-ICR-MS），用于鉴定考古脂质残留物。它是一种高分辨率、高灵敏度且检测限低的方法，能够鉴定低浓度的脂质化合物，从而为分析降解的脂质成分提供了一种极具潜力的新技术。我们针对分析陶瓷容器中煮熟和降解的食物残渣进行了全面的方法开发，并描述了最有效的样品制备方案。通过气相色谱-质谱联用（GC-MS）和气相色谱-燃烧-同位素比值质谱联用（GC-C-IRMS）进行独立平行分析所鉴定的成分，证明了其识别包括乳制品、脂肪以及水生来源脂质在内的多种不同食物残渣的能力。从实验煮熟的样品和原始考古样品中获得的结果证明了MALDI-FT-ICR-MS在分析考古有机残留物方面的适用性。样品制备方案和化合物鉴定为分析不同有机和矿物基质中各种老化和降解的脂质残留物提供了未来参考。
