Analysis of ancient mycolic acids by using MALDI TOF MS: response to “Essentials in the use of mycolic acid biomarkers for tuberculosis detection” by Minnikin et al., 2010

The mycobacterial cell wall is consists of several long chain lipid and glycolipid components. Mycolic acids are major and unique fraction of the cell envelope of mycobacteria that include the ancient causative agents of tuberculosis and leprosy. The analytical investigation of these lipid biomarker residues is one of the most promising perspectives in the field of molecular paleopathology. Recently published in this journal, Minnikin et al. present a systematic critique of the MALDI TOF MS analysis for determination of ancient mycolic acids, focusing on our previous paper. In this study, our mass spectrometric investigations by commonly used 2,5 DHB matrix were presented with our comments to the critique authors. On the base of our previous and recent mass spectrometric results we have to realize that the clinical protocols and standards cannot directly be used for the biomolecular paleopathological investigations. The applicability of the recent mycobacterial and clinical results is very limited in the biomolecular archaeology, thus the recent scientific results and protocols should be adapted carefully to bioarchaeological sciences.     

In situ decarboxylation of acetic and formic acids in aqueous inclusions as a possible way to produce excess CH4

Accurate reconstruction of diagenetic P‐T conditions in petroleum reservoirs from fluid inclusion data relies on valid measurements of methane concentration in aqueous inclusions. Techniques have been developed (Raman spectrometry) to provide sufficiently accurate data, assuming measured methane concentration has not been modified after aqueous inclusion entrapment. This study investigates the likelihood that organic acids derived from petroleum fluids and dissolved in formation water might suffer decarboxylation upon postentrapment heating within the fluid inclusion chamber, thereby generating excess CH₄ in the inclusions. Four different experiments were conducted in fused silica capillary capsules (FSCCs), mimicking fluid inclusions. The capsules were loaded with acetic (CH₃COOH) or formic (HCOOH) acid solution and were heated to 250°C for short durations (<72 h) in closed‐system conditions, with or without applying a fixed P_H2. Reaction products were characterized by Raman and FT‐IR spectrometry. Results indicate that decarboxylation reactions did take place, at variable degrees of progress, and that measurable excess CH₄ was produced in one experiment using acetic acid. This suggests that methane may be produced from dissolved organic acids in natural aqueous inclusions in specific situations, possibly inducing errors in the thermodynamic interpretation.     

弦歌台大成殿文物建筑彩绘颜料成分分析

弦歌台又被称为绝粮祠，整体布局以中轴线为中心呈现东西对称，现存建筑的规制为三进院落，从南向北依次为正门、戟门、大成殿、弦歌书院。大成殿作为弦歌台最核心的建筑，外观气势宏伟，彩绘精美绝伦，是我国东部地区规格较高的孔庙建筑之一。弦歌台大成殿在自然环境和人为因素的长期影响下，彩绘表面出现了褪色、龟裂、颜料脱落等多种病害，彩绘修复工作已成为当前文物保护亟待解决的棘手问题。本工作对彩绘样本的层位和形制进行详细分析，从剖面和表面等多角度进行全面研究，发现大部分彩绘样本由内向外的结构依次为基底层、地仗层、颜料层，蓝色彩绘样本所使用的地仗层为传统的单披灰工艺，与之不同的是红色彩绘样本为无地仗彩绘，红色颜料层直接绘制于基底层上，推测这可能与时代的发展及工艺的变化有关。为了更好地服务文物进行科学保护，需要了解大成殿彩绘颜料成分及制作工艺等。采用超景深微观分析、扫描电镜及能谱仪分析、显微拉曼光谱分析等现代技术及方法，对彩绘颜料样本进行了层位结构、微观及成分检测分析。结果表明，在制作工艺上，大成殿彩绘颜料层剖面多为两层以上叠加，是明显的重层彩绘，说明历史上至少经历过两次以上重绘。同时发现大成殿彩绘颜料层既有重...     

Identifying wine markers in ceramics and plasters using gas chromatography–mass spectrometry. Experimental and archaeological materials

The identification of the organic residues preserved in archaeological materials yields good insights into understanding food production, trade and consumption. Wine is one of the most important beverages produced, traded and consumed in the Mediterranean area. Consequently, it is important to identify its presence in ancient materials. Nevertheless, the identification of wine markers is still an object of discussion. We present here the results obtained from analysing different materials using gas chromatography/mass spectrometry (GC/MS), which allowed for the identification of tartaric acid and other markers of wine. The method was first tested on experimental and traditional materials that have been used until recently to store and/or produce wine and was then used for investigating archaeological materials. The experiments also involved the degradation of wine through cooking, drastic heating and burial for seven years. The results from the analysis of ceramic and plaster materials are discussed.     

五种含氯铜合金腐蚀产物的拉曼光谱及扫描电镜的分析研究

为深入研究五种含氯铜合金腐蚀产物(氯铜矿、斜氯铜矿、羟氯铜矿、氯磷钠铜石和铜氯矾)的拉曼光谱图,进一步补充金属锈蚀物的拉曼光谱库,采集不同考古来源的铜合金上腐蚀产物的拉曼光谱,并结合扫描电镜观察了腐蚀产物的形貌特征。研究结果表明,氯铜矿、斜氯铜矿和羟氯铜矿3个同分异构体的拉曼光谱并不相同:氯铜矿和斜氯铜矿较为常见,且经常混合在一起;羟氯铜矿不稳定,非常少见,一般与其他两种混合在一起。扫描电镜观察氯铜矿主要为粒状形貌,同时也发现有葡萄状、皮壳状、钟乳状等形貌;羟氯铜矿因少见,目前只观察到板状形貌。氯磷钠铜石腐蚀产物较厚且疏松柔软,常发现于干旱地区有动物或人遗骸墓葬的出土器物上,扫描电镜观察呈花瓣形状的蓓蕾形貌。铜氯矾更为少见,笔者目前只在2件器物上发现。同时对5种腐蚀产物的形成原因进行了讨论。     

广元千佛崖莲花洞彩绘颜料拉曼光谱分析

为了解广元千佛崖莲花洞造像的制作工艺与彩绘颜料成分,利用体视显微分析、金相显微分析、激光拉曼光谱分析技术对其进行物相和成分分析。分析结果表明,莲花洞造像彩绘直接绘制在岩石雕像表面,无底层。彩绘颜料分为多层,最多有三层,说明历史上至少有两次重绘。红色颜料为赤铁矿、朱砂;蓝色颜料主要为青金石与石青;绿色颜料为石绿、碱式氯化铜;白色颜料为硫酸铅。同时也表明,拉曼光谱分析彩绘颜料成分组成简便、快速、对样品要求量小,对样品无损分析,符合文物材质分析的要求,并可得到准确的信息。造像彩绘制作材料及工艺的分析结果为莲花洞造像彩绘保护研究提供了科学依据。     

夹砂陶器掺合料的初步研究

夹砂陶是陶器中非常重要的一个品种,特别是作为炊煮器是古人生活中不可或缺的日用器具。对夹砂陶器中掺合料的研究能够反映当时夹砂陶的制作工艺,也可以用来探讨掺合料的来源以及当时手工业分工以及产品的流通等问题。为此,本研究主要利用显微共聚焦拉曼光谱分析等技术手段对河南灵宝西坡遗址出土夹砂陶器中人工分离出的掺合料进行了初步分析,讨论了其中掺合料的类别、所占比重及来源。结果表明,西坡遗址出土的红褐色夹砂陶中掺合料的矿物成分主要以长石、石英、云母为主,而对样品及砂粒的称重结果表明,一些样品所用掺合料的比重可达20%左右。同时,对该遗址出土石料的分析表明,石料的物相组成与掺合料相似。另外,结合对良渚古城遗址夹砂陶器的分析结果,提出古代夹砂陶器的掺合料很有可能一部分来自于当时石器和玉器等加工废料的论断。研究成果为今后有关陶器掺合料的研究提出了新的方法和思路,同时也为探讨古代手工业生产的专业化模式提供依据。     

Raman spectroscopy and scanning electron microscopy confirm ochre residues on 71 000‐year‐old bifacial tools from Sibudu,South Africa

Micro‐residue analysis of stone tools is generally performed with optical light microscopy and the visual observations are then compared with experimental, replicated pieces. This paper complements such archaeological research by providing physico‐chemical evidence. Raman spectroscopy and scanning electron microscopy have been used to confirm the presence of hematite on red‐stained medial and proximal parts of 71 000‐year‐old Still Bay bifacial tools from Sibudu Cave. Our results confirm the conclusion from optical light microscopy that the tools were hafted with an ochre‐loaded adhesive. However, we point to some instances when hematite residues are incidental or may be inclusions in the rock used to make the stone tools.     

Stable carbon and nitrogen isotope ratios of bone collagen: Variations within individuals,between sexes,and within populations raised on monotonous diets

The stable carbon and nitrogen isotope ratios of collagen of seven bones from each of three rabbits raised on a monotonous diet, and of two bones from each of eight female and seven male mink raised on another monotonous diet, were determined. The ranges of δ¹³C values and δ¹⁵N values were 0·5‰ and 0·6‰ for the rabbit bones and 1·0‰ and 1·4‰ for the mink bones. Uncertainties in the δ¹³C and δ¹⁵N values for prehistoric human diets estimated from the isotopic composition of collagen from the small numbers of bones which are typically available for analysis, and thus likely to be of the order of ±1‰.     

Essentials in the use of mycolic acid biomarkers for tuberculosis detection: response to “High-throughput mass spectrometric analysis of 1400-year-old mycolic acids as biomarkers for ancient tuberculosis infection” by

High molecular weight long-chain mycolic acids are key structural components of the cell envelope of Mycobacterium tuberculosis and they are established as biomarkers for the identification of both ancient and modern tuberculosis. Mycolic acids from M. tuberculosis have a characteristic profile, reflecting contributions from five major distinct homologous series of mycolate structural types. Diagnosis of tuberculosis in archaeological material, using mycolic acid biomarkers, depends on objective recognition of the key characteristic mycolic acid components. A recent article in this journal claimed that tuberculosis could be confirmed in ancient bones by high throughput mass spectrometric analysis of mycolic acids. Scrutiny of the data presented reveals no convincing evidence for the presence of mycolic acids, characteristic of the M. tuberculosis complex, in the skeletal remains examined. This communication reviews the essential criteria necessary for positive tuberculosis diagnosis, using mycolic acids.