骨头/牙齿
推荐样品量：>1g
样品前处理：骨胶原提取
测试周期：2-3周
骨胶原是骨头样品最好的测年部分，保存完好的骨头呈褐色或棕色，光滑且略带光泽，表面比较坚硬，通常这
种样品能提取到较好的骨胶原蛋白。保存较差的骨头会呈白色或粉末状，矿物质积累也可以被识别，如锰和铁
元素，表明胶原蛋白流失。
Bone/tooth Samples Radiocarbon Analysis methods:
The bone is composed of three primary components: mineral, organic, and water. Approximately 30% of the dry sample weight comprises organic matter, while the remaining 70% consists of non-organic material. Within the organic fraction of bone, proteins and minimal lipid content are present. Collagen, the most significant protein, constitutes 90-95% of the total organic material and it is one of the most reliable fractions for dating.The preservation quality of bone collagen is mainly influenced by environmental factors. Collagen tends to be well-preserved in cooler climates and under moderate pH conditions. However, in highly acidic soils, the mineral part of the bone undergoes gradual dissolution, leading to the degradation of collagen.
Additionally, collagen is remarkably sensitive to chemical breakdown in highly alkaline soil environments.
The preparation of bone/tooth samples involves standard acid-base-acid (ABA)procedure and collagen extraction. Firstly, bone/toothsamples are ultrasonicated in ultrapure water, dried, grinded and sieved to get the appropriately sized sample fraction (0.5–1 mm).Then samples are treated with 0.5M hydrochloric acid (~18 hrs), 0.1-0.2M sodium hydroxide (30 min-1h), and 0.5M hydrochloricacid (1 hr). Bone/tooth collagen gelatinization is performed in pH 3 solution at 70°C for 20 hrs. Gelatine solution is filtered using acleaned filter and freeze-dried. The quality of collagen is monitored by carbon and nitrogen content in collagen, atomic C/N ratiodetermination and collagen yield. Samples are dated if the collagen yield is above 1% and the C:N ratio of the collagen is between 2.9 and 3.5. The samples that deviate from these ratios are deemed unsuitable for dating(van Klinken, G.J.,1999). The pure collagensamples were combusted with CuO and silver in vacuo to CO2 at 900ºC for 2 hrs. The CO2 was purified, graphitized and measured on a compact 0.5 MeV NEC Accelerator Mass Spectrometry in the Guangzhou Institute of Geochemistry, Chinese Academy of Sciences (Zhu et al., 2015).
If collagen of the sample is not suitable for dating, and you do not have an alternative suitable sample, we can perform AMS radiocarbon dating of bone from bioapatite. Bioapatite is a mineral component of bone, and carbonates within these materials can be targeted for dating. Please keep in mind that collagen reflects more reliable time range due to different uptake of carbon, but in the extraordinary cases it can still give a useful information.
1. van Klinken, G.J. (1999). Bone Collagen Quality Indicators for Palaeodietary and Radiocarbon Measurements, Journal of archaeological science, 26(6), pp. 687–695. Available at: https://doi.org/10.1006/jasc.1998.0385.
2. Zhu, S. Y., Ding, P., Wang, N., Shen, C. D., Jia, G. D., & Zhang, G. (2015). The compact AMS facility at Guangzhou Institute of Geochemistry, Chinese Academy of Sciences. Nuclear Instruments & Methods in Physics Research Section B-Beam Interactions with Materials and Atoms, 361, 72-75. https://doi.org/10.1016/j.nimb.2015.06.040
