Medieval manuscripts are invaluable archives of the written history of our past. Manuscripts can be dated and localized paleographically, but this method has its limitations. The Fragmenta membranea manuscript collection at the National Library of Finland has proved difficult to date using paleographic methods. Radiocarbon dating has been applied to manuscripts of parchment before, but a systematic protocol for radiocarbon dating of parchment has not been established with a minimally destructive sampling strategy. In this work, we have established a radiocarbon dating procedure for parchments combining a clean-room based chemical pretreatment process, elemental analyzer combustion, automatic graphitization and accelerator mass spectrometry (AMS) measurements to reduce the AMS target size from a typical 1 mg of carbon. Prolonged acid treatment resulted in improved dating accuracy, since this is consistent with the manufacturing process of medieval parchment involving a lime bath. Two different combustion processes were compared. The traditional closed tube combustion (CTC) method provided a well-established though labor-intensive way to produce 1 mg AMS targets. The Elemental Analyzer-based process (EA-HASE, Elemental Analyzer Helsinki Adaptive Sample prEparation line), is designed for fast combustion and smaller sample sizes. The EA-HASE process was capable of reproducing the simulated radiocarbon ages of known-age samples with AMS graphite target sizes of 0.3 mg of carbon, corresponding to a 3 mm2 area of a typical medieval parchment. The full potential of the process to go down to as little as 50 μg will be further explored in the future in parallel to studies of sample-specific contamination issues.

中文翻译：

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价值卷——为羊皮纸的放射性碳测年划定样本大小

中世纪手稿是我们过去书面历史的宝贵档案。手稿可以在古地理上注明日期和本地化，但这种方法有其局限性。事实证明，芬兰国家图书馆的 Fragmentamembrana 手稿收藏品很难使用古地理方法确定年代。放射性碳测年法之前已应用于羊皮纸手稿，但尚未建立具有最小破坏性采样策略的羊皮纸放射性碳测年系统协议。在这项工作中，我们为羊皮纸建立了放射性碳测年程序，结合了基于洁净室的化学预处理过程、元素分析仪燃烧、自动石墨化和加速器质谱 (AMS) 测量，以将 AMS 目标尺寸从典型的 1 mg 碳减少到. 长时间的酸处理提高了测年的准确性，因为这与涉及石灰浴的中世纪羊皮纸的制造过程是一致的。比较了两种不同的燃烧过程。传统的闭管燃烧 (CTC) 方法提供了一种行之有效但劳动密集型的生产 1 mg AMS 目标的方法。基于元素分析仪的过程（EA-HASE，元素分析仪赫尔辛基自适应样品制备线）专为快速燃烧和更小的样品量而设计。EA-HASE 工艺能够重现已知年龄样品的模拟放射性碳年龄，AMS 石墨靶尺寸为 0.3 毫克碳，对应于 3 毫米 比较了两种不同的燃烧过程。传统的闭管燃烧 (CTC) 方法提供了一种行之有效但劳动密集型的生产 1 mg AMS 目标的方法。基于元素分析仪的过程（EA-HASE，元素分析仪赫尔辛基自适应样品制备线）专为快速燃烧和更小的样品量而设计。EA-HASE 工艺能够重现已知年龄样品的模拟放射性碳年龄，AMS 石墨靶尺寸为 0.3 毫克碳，对应于 3 毫米 比较了两种不同的燃烧过程。传统的闭管燃烧 (CTC) 方法提供了一种行之有效但劳动密集型的生产 1 mg AMS 目标的方法。基于元素分析仪的过程（EA-HASE，元素分析仪赫尔辛基自适应样品制备线）专为快速燃烧和更小的样品量而设计。EA-HASE 工艺能够重现已知年龄样品的模拟放射性碳年龄，AMS 石墨靶尺寸为 0.3 毫克碳，对应于 3 毫米2典型的中世纪羊皮纸的区域。未来将在研究特定样品污染问题的同时，进一步探索该过程降低至 50 μg 的全部潜力。