The Mayan Codex of Mexico (MCM), the only Mayan codex found in the 20th century, was unveiled in 1971 during the Ancient Maya Calligraphy exhibition at Club Grolier. The codex comprises 10 pages of bark paper in accordion format, coated with a layer of plaster on both sides. It illustrates the synodic cycles of Venus, with its four phases. Since its discovery, the MCM has been subject to controversy and discussions about its authenticity. In 2016, a group of specialists led by Baltazar Brito chief of the National Library of Anthropology and History, carried out an exhaustive study of the codex with the purpose of determining its temporality and authenticity. In this work, the pre-Columbian authenticity of the codex is verified by the radiocarbon (14C) technique using AMS. Two cleaning procedures were contrasted: the standard acid-base-acid (ABA) protocol and a second one with Soxhlet plus ABA. Results obtained when samples were prepared following ABA protocol only, placed the age of the bark paper between 991 and 1147 cal AD. The second cleaning method with Soxhlet plus ABA, resulted in younger ages, between 1159 and 1261 cal AD. However, we consider that when Sohxlet is used as part of the cleaning protocol, organic contaminants are reduced to a minimum, and 14C dates are more reliable. These results indicate that the vegetal support of the MCM belongs to Postclassical Mayan period and place it as the oldest known manuscript of America found to date.

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重新审视墨西哥玛雅法典的 AMS 14C 日期

墨西哥玛雅手抄本 (MCM) 是 20 世纪唯一发现的玛雅手抄本，于 1971 年在格罗利尔俱乐部举办的古代玛雅书法展上亮相。该手抄本由 10 页手风琴格式的树皮纸组成，两面都涂有一层石膏。它说明了金星的会合周期，分为四个阶段。自发现以来，MCM一直受到对其真实性的争议和讨论。2016 年，由国家人类学和历史图书馆馆长 Baltazar Brito 领导的一组专家对抄本进行了详尽的研究，旨在确定其时间性和真实性。在这项工作中，该法典的前哥伦布时期真实性通过放射性碳 (14C) 使用 AMS 的技术。对比了两种清洁程序：标准酸碱酸 (ABA) 方案和第二个使用索氏加 ABA 的方案。仅按照 ABA 协议制备样品时获得的结果，将树皮纸的年龄置于公元 991 年至 1147 年之间。使用 Soxhlet 加 ABA 的第二种清洁方法导致年龄更小，介于公元 1159 年和 1261 年之间。然而，我们认为当 Sohxlet 用作清洁方案的一部分时，有机污染物会减少到最低限度，并且14C 日期更可靠。这些结果表明 MCM 的植物支持属于后古典玛雅时期，并将其列为迄今为止发现的美国最古老的手稿。