Chemical Removal of Conservation Substances by “Soxhlet“-Type Extraction
Chemical Removal of Conservation Substances by “Soxhlet“-Type Extraction
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通过“索氏”萃取化学去除保护物质
DOI：
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发表时间：
2001
期刊：
影响因子：
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通讯作者：
M. Nadeau
中科院分区：
文献类型：
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作者：
F. Bruhn;A. Duhr;P. Grootes;Annette Mintrop;M. Nadeau
在莱布尼茨放射性碳实验室，艺术品和考古物品通常经过化学保存，因此可能受到 14C 含量的污染，使用计算机控制的“索氏”型系列提取器进行处理。该装置采用不同溶剂的沸腾和冷凝的连续程序，在恒定的工艺条件下进行萃取和真空过滤。选择了可溶解大多数常用保护化学品的五种溶剂的洗脱液序列。通过随后的加速器质谱 (AMS) 测量对参考木材样品中的这些不同污染物进行的研究表明，它们的有效去除取决于使用足够的溶剂。对于许多污染物（例如木胶、甲基纤维素、Klucel®、糖和聚乙二醇），常规酸碱酸 (AAA) 处理已经产生了令人满意的结果，而对于 Caparol® 和蜂蜡，使用丙酮、甲醇、水相对“温和”的处理以及随后的标准 AAA 提取就足够了。只有使用我们的全套溶剂才能完全去除橡胶胶、环氧树脂和石蜡。当没有或仅有不完整的有关保护材料类型的信息可用时，后一种程序也适用。对于环氧树脂来说，污染物似乎富含碱残留物，而易溶的“腐植酸”部分，即使经过标准 AAA 处理，也能得到令人满意的结果。介绍了提取程序应用的两个案例研究。
At the Leibniz radiocarbon lab, art and archaeological objects, often chemically conserved and thus potentially contaminated with respect to their 14C content, are treated using a computer-controlled “Soxhlet”-type series extractor. This device uses a continuous procedure of boiling and condensation of different solvents for extraction and vacuum filtration under constant process conditions. An elutrope sequence of five solvents that dissolve most customary conservation chemicals was selected. A study of these different contaminants applied to reference wood samples with subsequent accelerator mass spectrometry (AMS) measurements demonstrates that their effective removal is dependent on the use of adequate solvents. For many contaminants (e.g. wood glue, methyl cellulose, Klucel®, sugar, and polyethylene glycol), routine acid-alkali-acid (AAA) treatment already yields satisfactory results, whereas for Caparol® and beeswax a relatively “mild” treatment with acetone, methanol, water, and subsequent standard AAA extraction is sufficient. Complete removal of rubber glue, epoxy resin, and paraffin can only be accomplished with our full set of solvents. The latter procedure is also appropriate when no or only incomplete information about the type of conservation material is available. For epoxy resin the contamination appears to be enriched in the alkali residue, and the easily soluble “humic acid” fraction, even after standard AAA treatment, gives satisfactory results. Two case studies on the application of the extraction procedures are presented.