In recent years, there has been a surge in the number of applications of Fourier-transform mid-infrared (FTIR) spectroscopy for the characterization of environmental samples and prediction of some of their properties whose measurement has traditionally involved time-consuming and costly methods. However, there are several different mid-infrared techniques available, and there is a gap in knowledge regarding the best-suited technique for recording informative spectra of different types of environmental samples. This study compared the three most widespread FTIR techniques using solid and liquid samples. A total of 11 environmental samples belonging to four categories were analyzed with attenuated total reflectance (ATR), photoacoustic (PAS), and diffuse reflectance (DR) FTIR spectroscopy. Overall, PAS-FTIR was the best technique, providing a greater amount of information, especially for opaque samples (i.e., organic waste, biochar, and soil), than ATR-FTIR and DR-FTIR spectroscopy. Attenuated total reflectance FTIR provided the best spectra for soft samples, such as plant materials, probably due to their ability to achieve good optical contact with the ATR crystal. Finally, DR-FTIR performed relatively well for most samples but was found to be more sensitive to moisture in the samples, resulting in noise in specific areas, and was less sensitive in bond vibrations related to Si.

中文翻译：

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用于表征生物有机样品的三种不同 FTIR 采样技术（漫反射、光声和衰减全反射）的比较

近年来，傅里叶变换中红外 (FTIR) 光谱用于表征环境样品和预测其某些特性的应用数量激增，其测量传统上涉及耗时且昂贵的方法。然而，有几种不同的中红外技术可用，并且在记录不同类型环境样本的信息光谱的最合适技术方面存在知识空白。本研究比较了使用固体和液体样品的三种最广泛使用的 FTIR 技术。使用衰减全反射 (ATR)、光声 (PAS) 和漫反射 (DR) FTIR 光谱分析了属于四个类别的总共 11 个环境样品。总的来说，PAS-FTIR 是最好的技术，提供比 ATR-FTIR 和 DR-FTIR 光谱更多的信息，尤其是对于不透明样品（即有机废物、生物炭和土壤）。衰减全反射 FTIR 为软样品（例如植物材料）提供了最佳光谱，这可能是因为它们能够与 ATR 晶体实现良好的光学接触。最后，DR-FTIR 对于大多数样品表现相对较好，但发现对样品中的水分更敏感，导致特定区域出现噪声，并且对与 Si 相关的键振动不太敏感。可能是因为它们能够与 ATR 晶体实现良好的光学接触。最后，DR-FTIR 对于大多数样品表现相对较好，但发现对样品中的水分更敏感，导致特定区域出现噪声，并且对与 Si 相关的键振动不太敏感。可能是因为它们能够与 ATR 晶体实现良好的光学接触。最后，DR-FTIR 对于大多数样品表现相对较好，但发现对样品中的水分更敏感，导致特定区域出现噪声，并且对与 Si 相关的键振动不太敏感。