Identification of surface dyeing agents of two bookbinding leathers from 19th-century Qajar,Iran, using LC–MS, μXRF and FTIR spectroscopy

Identifying tanning and dyeing agents of historical leathers is one of the less studied subjects. Therefore, this study aims to distinguish the surface dyeing agent of historical leathers along with the tanning agents. It helps to better understand the leather-making process of past centuries. For this purpose, two Iranian historical bookbinding leathers belonging to the Qajar era were investigated. The tannins were examined by ferric spot test and ATR-FTIR spectroscopy after being extracted from the leather corium layer. ATR-FTIR and μXRF spectroscopy were also used to study the characteristics of the leathers' surface, in both grain and corium layers. LC–MS was also used to analyze the extracts taken from the surface of the leather samples. The results showed the corium layer of leathers has a significant number of hydrolysable tannins, especially gallotannins, as tanning agents. The characteristics of their FTIR spectra are significantly similar to those of sumac. LC–MS results showed the presence of ellagic acid, as an indicator analyte, on the surface of the leathers. It indicates that tannin-rich plants, such as oak, have been used for dyeing these leathers. Investigation of the structural properties of the grain and corium layers also revealed the accumulation of copper and iron on the surface of the leathers. Accordingly, copper and iron, which reacted with tannins to give a black color, were the main dyeing factor used in both historical leather samples.     

Chemical evidence for wine production around 4000 BCE in the Late Chalcolithic Near Eastern highlands

Archaeological excavations in the Areni-1 cave complex in southeastern Armenia revealed installations and artifacts dating to around 4000 cal. BCE that are strongly indicative of wine production. Chemical evidence for this hypothesis is presented here using a new method to detect the anthocyanin malvidin that gives grapes and pomegranates their red color. Using solid phase extraction (SPE) and alkaline treatment of the samples, followed by combined liquid chromatography-tandem mass spectrometry (LC-MS/MS), this method was applied to authentic standards and four ancient potsherds from Armenia and Syria. A positive result was observed for two of the samples from the Areni-1 cave complex, adding evidence supporting the hypothesis that wine was produced in the Near Eastern highlands in the Late Chalcolithic Period.     

博物馆环境空气中五种有机酸的定量分析——离子色谱法

木质及纸质材料是博物馆环境空气中有机酸最主要的来源,所释放出的挥发性有机酸包含甲酸、乙酸、丙酸、丁酸、戊酸等短链脂肪酸。这些有机酸气体会导致青铜文物的腐蚀,铅质器物表面的风化,珐琅、陶器的腐蚀脆化,丝织品纤维的劣化,纸张寿命的缩短等。为此,本研究建立了一种基于离子色谱同时测定博物馆环境空气中甲酸、乙酸、丙酸、丁酸和戊酸等5种挥发性有机酸浓度的方法。以超纯水作为吸收液,吸收液体积为10 mL,采集流量为400 mL/min,主动采样法采集博物馆环境空气样品。采用5 mmol/L KOH淋洗液等度洗脱,在9 min内可同时测定五种挥发性有机酸的浓度。结果表明,在0.05～0.50μg/mL的线性范围内,甲酸根、乙酸根、丙酸根、丁酸根、戊酸根的标准曲线的相关系数均高于0.995,检出限为0.001～0.009μg/mL,定量限为0.004～0.030μg/mL;五种有机酸根的加标回收率为91.4%～107.4%。库房A中检测到的甲酸、乙酸的浓度范围分别为36.40～85.44μg/m³,274.42～312.11μg/m³;库房B中检测到的甲酸、乙...     

明代丝织物保存状态的分析研究

考古出土丝绸保存状态的研究对丝绸的科学保护具有重要的指导意义。本工作选取丝纤维中最主要的桑蚕丝及柞蚕丝作参照,以考古出土的明代丝绸为研究对象,通过荧光电子显微镜观察丝绸的纤维结构形貌、傅立叶变换红外光谱仪分析化学结构,结合X-射线衍射仪分析结晶度,用薄层色谱分析丝绸中氨基酸的组成,并进一步用紫外-可见光分光光度法分析丝绸中酪氨酸含量等方法,对一件出土的明代丝绸织物的保存状态进行了科学分析研究。分析结果表明,明代丝绸为桑蚕丝,纤维丝松散且断裂较多,结晶度下降,多数氨基酸含量明显降低,只检测到甘氨酸、丙氨酸、丝氨酸、酪氨酸与谷氨酸。酪氨酸含量为13.78%,比参照桑蚕丝含量低。     

馆藏砖石质文物有害盐中多种无机及有机酸阴离子的定量分析

博物馆环境空气中无机或有机酸性污染气体会腐蚀馆藏砖石质文物并使其表面出现有害盐。常见的有害盐种类复杂，可能同时含有无机和有机酸阴离子。为进一步认识文物盐害和分析盐害产生的原因，本研究建立了一种基于离子色谱的有害盐中无机和有机酸阴离子定量分析方法。该方法可同时测定馆藏砖石质文物上有害盐中氟离子、氯离子、溴离子、硝酸根、亚硝酸根、磷酸根、硫酸根、甲酸根、乙酸根、丙酸根、丁酸根、戊酸根等十二种阴离子。采用2～30 mmol/L KOH淋洗液梯度洗脱，能够在35 min的检测时间下实现该十二种阴离子的快速分离与准确检测。所有阴离子的标准曲线的相关系数均高于0.995,检出限为0.001～0.022μg/mL,定量限为0.004～0.073μg/mL;加标回收率为81.8%～107.0%。该方法采用超纯水作为溶剂，样品处理简单，易于操作；具有成本低廉、检测时间短和准确性高的特点；可定量计算有害盐中多种无机及有机酸阴离子的质量分数。将该方法应用于中国国家博物馆馆藏“汉并天下”瓦当和仿制玉炉表面有害盐中的无机及有机酸阴离子的分析，可为分析盐害发生的原因，阻止、延缓及预测盐害的发生提供依据。     

文物彩绘常用胶料的氨基酸组成 及红外光谱特征研究

为了探索鉴定古代文物彩绘胶料的综合分析方法,使用红外光谱仪及氨基酸分析仪对中国古代五种常用文物彩绘胶料的红外吸收光谱及氨基酸组成进行了测定。通过对样品红外光谱特征吸收峰的判别、分析,得出了1653cm-1及1545cm-1处的吸收峰为蛋白类胶料的特征,1076cm-1及1043cm-1处的吸收峰为桃胶的特征,以及奶类同时具有蛋白类胶料及桃胶特征的结果。通过对样品氨基酸组成的分析,得出了动物胶特有羟脯氨酸及较多的甘氨酸,鸡蛋含有较高的天冬氨酸和较低的脯氨酸,奶类的谷氨酸和丙氨酸含量比较高的结果。研究结果表明,通过氨基酸分析结合红外光谱的特征吸收峰,可以基本区分、判定古代文物彩绘常用胶料归属的结论。