Istituto di Scienze del Patrimonio Culturale, Consiglio Nazionale delle Ricerche, ISPC-CNR, Via R. Cozzi 53, Milano 20125, Italy.
Department of Chemical Engineering, Imperial College London, South Kensington Campus London, London SW7 2AZ, United Kingdom.
Anal Chem. 2021 Nov 9;93(44):14635-14642. doi: 10.1021/acs.analchem.1c02392. Epub 2021 Oct 26.
In this study, the novel application of ATR-FTIR spectroscopy and macro ATR-FTIR spectroscopic imaging overcame an analytical challenge in conservation science: the time-resolved, chemical, and spatial investigation of the reaction of inorganic treatments for stone conservation (ammonium oxalate, AmOx; ammonium phosphate, DAP) occurring in water-based solutions. The aim was to (1) assess the composition and localization of reaction products and their phase variation during the reaction in real time and directly in an aqueous environment and (2) investigate the reaction of AmOx and DAP with calcite and the transformations induced to the substrate with a time-resolved approach. The new analytical results showed that for both treatments, the formation of new crystalline phases initiated at the early stages of the reaction. Their composition changed during the treatment and led to more stable phases. The reactivity of the stone substrate to the treatments varied as a function of the stone material features, such as the specific surface area. A clear influence of post-treatment rinsing on the final composition of reaction phases was observed. Above all, our research demonstrates the actual feasibility, practicality, and high potential of an advanced ATR-FTIR spectroscopic approach to investigate the behavior of conservation treatments and provided new analytical tools to address the choices of conservation in pilot worksites. Lastly, this study opens novel analytical perspectives based on the new possible applications of ATR-FTIR spectroscopic imaging in the field of conservation science, materials science, and analytical chemistry.
在这项研究中，ATR-FTIR 光谱和宏观 ATR-FTIR 光谱成像的新应用克服了保护科学中的一个分析挑战：即时、化学和空间研究无机处理剂（草酸铵、AmOx；磷酸铵、DAP）在水基溶液中对石材保护的反应。目的是：(1) 评估反应产物的组成和定位及其在水溶液中实时直接反应过程中的相变化；(2) 用时间分辨方法研究 AmOx 和 DAP 与方解石的反应以及对基质的转化。新的分析结果表明，对于两种处理方法，新的晶相在反应的早期阶段开始形成。它们的组成在处理过程中发生变化，导致更稳定的相。石材基质对处理的反应性随石材材料特性（如比表面积）而变化。观察到后处理冲洗对反应相最终组成的明显影响。总之，我们的研究证明了先进的 ATR-FTIR 光谱方法在研究保护处理行为方面的实际可行性、实用性和巨大潜力，并为在试点工地进行保护提供了新的分析工具。最后，这项研究基于 ATR-FTIR 光谱成像在保护科学、材料科学和分析化学领域的新可能应用，开辟了新的分析视角。
