Anuschek Moritz, Bawuah Prince, Zeitler J Axel
Department of Chemical Engineering and Biotechnology, University of Cambridge, Philippa Fawcett Drive, CB3 0AS Cambridge, UK.
Department of Pharmacy, Pharmaceutical Technology and Biopharmaceutics, Ludwig-Maximilians-University, Butenandtstraße, Munich, Germany.
Int J Pharm X. 2021 Apr 27;3:100079. doi: 10.1016/j.ijpx.2021.100079. eCollection 2021 Dec.
Terahertz time-domain spectroscopy (THz-TDS) is a novel technique which has been applied for pore structure analysis and porosity measurements. For this, mainly the anisotropic Bruggeman (AB-EMA) model is applied to correlate the effective refractive index ( ) of a tablet and the porosity as well as to evaluate the pore shape based on the depolarisation factor . This paper investigates possible error sources of the AB-EMA for THz-TDS based tablet analysis. The effect of absorption and tablet anisotropy - changes of pore shape with porosity and density distribution - have been investigated. The results suggest that high tablet absorption has a negligible effect on the accuracy of the AB-EMA. In regards of tablet anisotropy the accuracy of the porosity determination is not impaired significantly. However, density distribution and variations in the pore shape with porosity resulted in an unreliable extraction of the tablet pore shape. As an extension of the AB-EMA a new concept was introduced to convert the model into bounds for . This new approach was found useful to investigate tablet pore shape but also the applicability of the AB-EMA for an unknown set of data.
太赫兹时域光谱技术（THz - TDS）是一种已应用于孔隙结构分析和孔隙率测量的新技术。为此，主要应用各向异性布鲁格曼（AB - EMA）模型来关联片剂的有效折射率（ ）与孔隙率，并基于去极化因子评估孔隙形状。本文研究了基于太赫兹时域光谱技术的片剂分析中AB - EMA模型可能存在的误差来源。研究了吸收和片剂各向异性的影响——孔隙形状随孔隙率和密度分布的变化。结果表明，高片剂吸收率对AB - EMA模型的准确性影响可忽略不计。就片剂各向异性而言，孔隙率测定的准确性并未受到显著损害。然而，密度分布以及孔隙形状随孔隙率的变化导致片剂孔隙形状的提取不可靠。作为AB - EMA模型的扩展，引入了一个新概念，将该模型转换为 的边界。发现这种新方法不仅有助于研究片剂孔隙形状，还能用于研究AB - EMA模型对未知数据集的适用性。
