Birch bark tar was used extensively throughout human history. While later ceramic-based production technologies are known, prehistoric aceramic techniques leave little to no archaeological evidence. Experimental tar production attempts to fill this gap and suggest potential techniques. However, their archaeological relevance is unclear. Through an in-depth biomolecular analysis using Gas Chromatography-Mass Spectrometry, this study attempts to differentiate tars produced using four experimental aceramic techniques: condensation, ash mound, pit roll, and raised structure. In doing so we publish the largest collection of GC-MS results of aceramic birch tars. The results show that pentacyclic triterpenoids, characteristic of birch bark, vary between the production techniques in relation to heating exposure and perhaps the tar collection method. This allows for a tentative identification of tars produced through the condensation and ash mound techniques, which were formed consistently using short periods of heating and collected systematically by scraping. In contrast, tars produced using the pit roll and raised structure techniques do not have consistent molecular signatures. Despite the partial success of Gas Chromatography-Mass Spectrometry, the archaeological relevance is questioned because this technique is only applicable to samples from optimum lipid preservation conditions when a high number of pentacyclic triterpenoids are preserved. Therefore, using Gas Chromatography-Mass Spectrometry to determine the transformation methods of organics, like birch bark, may not be an appropriate standalone technique to fairly discuss the technological capabilities of past populations.

中文翻译：

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使争论复杂化：评估气相色谱-质谱分析法区分史前陶瓷焦油生产技术的潜力

桦树皮焦油在整个人类历史中被广泛使用。虽然后来的陶瓷生产技术已为人所知，但史前陶瓷技术几乎没有留下任何考古证据。焦油生产实验试图填补这一空白并提出潜在的技术。然而，它们的考古意义尚不清楚。通过使用气相色谱-质谱法进行深入的生物分子分析，本研究尝试区分使用四种实验陶瓷技术产生的焦油：冷凝、灰堆、坑滚和凸起结构。为此，我们发布了最大的陶瓷桦焦油 GC-MS 结果集。结果表明，作为白桦树皮特征的五环三萜类化合物在与加热暴露相关的生产技术以及可能的焦油收集方法之间存在差异。这使得可以对通过冷凝和灰堆技术产生的焦油进行初步鉴定，这些焦油是通过短时间的加热一致形成的，并通过刮擦系统地收集。相比之下，使用坑滚和凸起结构技术生产的焦油不具有一致的分子特征。尽管气相色谱-质谱法取得了部分成功，但其考古学相关性受到质疑，因为该技术仅适用于保存大量五环三萜类化合物时来自最佳脂质保存条件的样品。因此，使用气相色谱-质谱法来确定有机物（如桦树皮）的转化方法可能不是一个适当的独立技术来公平地讨论过去人类的技术能力。