Development of desorption electrospray mass spectrometry (DESI-MS) for analysis of ancient lipids from food residues on archaeological artefacts

从考古文物中提取脂质并进行质谱分析以获得有关文物的信息，这一方法已得到很好的建立，并开始用于解决具有国际意义的高调考古问题。为了充分发挥其潜力，这些方法需要应用于来自广泛背景和地点的大量文物（例如陶瓷容器）。然而，这些提取物的LC-或衍生化/GC-MS分析是耗时的，并且由于通常少于一半的这种提取物含有可检测的脂质水平，因此通常令人沮丧和浪费。因此，快速、方便、中等通量的方法来筛选这些提取物并获得关于其组分的结构信息将极大地促进分析，并允许对随后的LC-或GC-MS分析的样品进行优先排序。DESI能够在环境条件下直接从几乎任何表面解吸和MS分析物。该方法简单、灵敏、快速，与MS/MS方法兼容。我们已经认识到了DES-MS在考古应用中的潜力，为我们的质谱仪建立了DESI源，并证明了其在典型考古材料表面脂质分析中的可行性。虽然直接从文物表面进行DESI分析很有吸引力，但很少有人能将文物从博物馆收藏品中取出到MS实验室进行分析。但是，专家可以从陶瓷表面取出少量样品，进行提取和GC或LC-MS分析。初步数据表明，成功的直接EST-MS/MS分析非常小的等分试样的这种脂质提取物的考古陶瓷，干燥到玻璃或塑料60孔板，以及EST-FT-ICR-MS分析的脂肪酸在这样的提取物。因此，该奖学金将利用高科技分析设施约克质谱卓越中心（CoEMS）中最先进的质谱仪，开发用于快速筛选和第一阶段分析考古文物脂质提取物的质谱-MS/MS。学生将使用中分辨率和高分辨率质谱仪，优化载玻片或多孔板解吸提取物中甘油三酯，脂肪酸和甾醇的EST-MS/MS，并确定检测限。我们已经从不同环境中的各种人种学，历史和考古文物中存档了500多个脂质提取物，以及所有样品的高温GC和GC-MS数据。学生将访问此存档以优化方法，并测试检测限。然后，将对来自巨石阵世界遗产的数百件陶瓷器皿的选定提取物进行EST-MS/MS测试。筛选这些提取物，以确定样品进行GC和LC-MS后续分析将提供大量节省资源和研究人员的时间，使更深入的采样，从而推断。申请这个备受瞩目的网站还将“展示”该方法，并让学生接触到更广泛的考古界和媒体。CoEMS为我们的博士生在与NERC-RSC计划直接相关的领域提供了一个独特的培训计划，提供专门针对博士生使用高科技仪器的需求量身定制的研究生课程。除了卓越的网络和CoEMS的培训机会，学生将属于分析科学和环境化学研究小组，并通过BioArchh，考古学，生物学和化学的合资企业在约克的成员获得令人羡慕的和不寻常的多学科培训。我们的项目合作伙伴是使用成熟的LC和GC-MS方法分析文物中脂质的先驱，也代表了博物馆用户社区，进一步扩展了该项目提供的独特培训。

The extraction and mass spectrometric analysis of lipids from archaeological artefacts to gain information regarding the artefact is well established and beginning to be used to tackle high profile archaeological questions of international significance. To realise their full potential, such methods need to be applied to large numbers of artefacts (e.g. ceramic vessels) from a wide range of contexts and sites. However, LC- or derivatisation/GC-MS analyses of these extracts are time consuming and, since generally less than half of such extracts contain detectable lipid levels, often frustrating and wasteful. Consequently, a rapid, convenient, medium throughput approach to screening such extracts and obtaining structural information on their components would greatly facilitate analysis and allow prioritisation of samples for subsequent LC- or GC-MS analysis. DESI enables desorption and MS of analytes under ambient conditions directly from almost any surface. It is simple, sensitive, very rapid, and compatible with MS/MS approaches. We have recognised the potential of DESI-MS for archaeological applications, built a DESI source for our mass spectrometers, and shown its feasibility for lipid analysis from surfaces of typical archaeological materials. Although DESI analysis directly from artefact surfaces is appealing, it is rare that artefacts can be removed from museum collections to the MS lab for analysis. However, removal by experts of small samples of the surface of the ceramic, for extraction and GC- or LC- MS analysis is accepted. Preliminary data show successful direct DESI-MS/MS analysis of very small aliquots of such lipid extracts of archaeological ceramics, dried onto glass or into plastic 60-well plates, as well as DESI-FT-ICR-MS analysis of fatty acids in such extracts. This studentship will thus exploit the state-of-the-art mass spectrometers available in the high technology analytical facility, the York Centre of Excellence in Mass Spectrometry (CoEMS), to develop DESI-MS/MS for the rapid screening and first stage analysis of lipid extracts of archaeological artefacts. The student will optimise DESI-MS/MS for triacylgycerides, fatty acids and sterols in extracts desorbed from glass slides or multi-well plates, using medium and high resolution mass spectrometers, and determine limits of detection. We have archived over 500 lipid extracts from a wide range of ethnographic, historical and archaeological artefacts from different environments, and high temperature-GC and GC-MS data from all samples. The student will access this archive to optimise the approach, and test limits of detection. DESI-MS/MS will then be tested on selected extracts of the several hundred ceramic vessels from the Stonehenge World Heritage Site. Screening these extracts to identify samples for subsequent analysis by GC- and LC-MS will offer a massive saving in resources and investigator time, enabling deeper sampling and thus inference. Application to this high profile site will also 'showcase' the method and expose the student to the wider archaeological community and the media. The CoEMS provides a unique focus for a coherent and innovative programme of training for our PhD students in areas directly relevant to the NERC-RSC initiative, providing graduate level courses tailored specifically to the needs of PhD students working with high technology instrumentation. In addition to the outstanding networking and training opportunities of CoEMS, the student will belong to the Analytical Science and Environmental Chemistry research group, and gain enviable and unusual multidisciplinary training via membership of BioArCh, a joint venture of Archaeology, Biology and Chemistry at York. Our project partners are pioneers in the analysis of lipids from artefacts using established LC- and GC-MS approaches, and also represent the museum user community, further extending the unique training offered by this project.