Research Institute of Wood Industry, Chinese Academy of Forestry, Dongxiaofu No.1, Beijing 100091, China.
Zhejiang Provincial Institute of Cultural Relics and Archaeology, Jiaogong road No.71, Hangzhou 310012, Zhejiang China.
Anal Chem. 2020 Jul 21;92(14):9908-9915. doi: 10.1021/acs.analchem.0c01429. Epub 2020 Jul 13.
Evaluating the deterioration state of archeological wood is obligatory before the preservation of archeological wooden artifacts. Herein, a nondestructive, accurate, and rapid methodology is first developed via direct analysis in real time-mass spectrometry (DART-MS) with chemometrics to classify archeological wood and recent wood into 3 groups according to their deterioration states. As water in wooden artifacts probably affected the ion fragmentation process during DART-MS, ions responsible for evaluating the deterioration state were separately screened toward waterlogged archeological wood and dried archeological wood by partial least-squares discriminant analysis (PLS-DA). The well-defined separation of severely decayed archeological wood, moderately decayed archeological wood and recent wood was revealed in PLS-DA models. Twenty and 27 wood fragment ions were further screened as key variables to evaluate the deterioration state of waterlogged archeological wood and dried archeological wood, respectively. They were tentatively identified as ions of lignin monomeric compositions, lignin dimers, lignin trimers, and oligosaccharides. Results strongly suggested that differences in the structure and relative abundances of wood cell wall components accounts for the evaluation of deterioration state by DART-MS coupled to chemometrics. PLS-DA models provided = 0.836, = 0.817, and = 0.754, = 0.682 were then established separately using mass spectral fingerprints of respective potential predictive wood fragment ions. Furthermore, archeological woods, consisting of , , , , and species and with an average MWC range of 103-465%, were used as an external validation set and evaluated with the methodology developed herein and the MWC criteria. Results showed that DART-MS coupled to chemometrics could accurately predict the inhomogeneous deterioration states of archeological wooden artifacts and avoid the interference of inorganic deposits, in comparison with the MWC criteria.
评估考古木材的劣化状态是保护考古木质文物的必要前提。在此，我们首次通过实时直接分析-质谱法（DART-MS）结合化学计量学建立了一种无损、准确且快速的方法，根据其劣化状态将考古木材和近期木材分为 3 组。由于水可能会影响 DART-MS 过程中的离子碎裂，因此通过偏最小二乘判别分析（PLS-DA）分别筛选负责评估劣化状态的离子，以研究水饱和考古木材和干燥考古木材。PLS-DA 模型清楚地显示了严重腐朽的考古木材、中度腐朽的考古木材和近期木材的良好分离。进一步筛选出 20 个和 27 个木材碎片离子，分别作为评估水饱和考古木材和干燥考古木材劣化状态的关键变量。它们被初步鉴定为木质素单体组成、木质素二聚体、木质素三聚体和低聚糖的离子。结果强烈表明，细胞壁成分的结构和相对丰度的差异是通过 DART-MS 结合化学计量学评估劣化状态的原因。然后分别使用各自潜在预测性木材碎片离子的质谱指纹图谱，建立了 PLS-DA 模型，其 = 0.836、 = 0.817 和 = 0.754、 = 0.682。此外，由 、 、 、 和 种组成，平均 MWC 范围为 103-465%的考古木材，作为外部验证集，并用本文建立的方法和 MWC 标准进行评估。结果表明，与 MWC 标准相比，DART-MS 结合化学计量学可以准确预测考古木质文物不均匀的劣化状态，同时避免了无机沉积物的干扰。
