Yeh Yen-Cheng, Haasdonk Bernard, Schmid-Staiger Ulrike, Stier Matthias, Tovar Günter E M
Fraunhofer Institute for Interfacial Engineering and Biotechnology IGB, Stuttgart, Germany.
Institute of Interfacial Process Engineering and Plasma Technology, University of Stuttgart, Stuttgart, Germany.
Front Bioeng Biotechnol. 2023 Mar 16;11:1116735. doi: 10.3389/fbioe.2023.1116735. eCollection 2023.
The Bouguer-Lambert-Beer law is widely used as the fundamental equation for quantification in absorption spectroscopy. However, deviations from the Bouguer-Lambert-Beer law have also been observed, such as chemical deviation and light scattering effect. While it has been proven and shown that the Bouguer-Lambert-Beer law is valid only under very restricted limitations, there are only a few alternatives of analytical models to this law. Based on the observation in the experiments, we propose a novel model to solve the problem of chemical deviation and light scattering effect. To test the proposed model, a systematic verification was conducted using potassium dichromate solutions and two types of microalgae suspensions with varying concentrations and path lengths. Our proposed model demonstrated excellent performance, with a correlation coefficient ( ) exceeding 0.995 for all tested materials, significantly surpassing the Bouguer-Lambert-Beer law, which had an as low as 0.94. Our results confirm that the absorbance of pure pigment solutions follows the Bouguer-Lambert-Beer law, while the microalgae suspensions do not due to the light scattering effect. We also show that this scattering effect leads to huge deviations for the commonly used linear scaling of the spectra, and we provide a better solution based on the proposed model. This work provides a powerful tool for chemical analysis and especially for the quantification of microorganisms, such as the concentration of biomass or intracellular biomolecules. Not only the high accuracy but also the simplicity of the model makes it a practical alternative to the existing Bouguer-Lambert-Beer law.
布格-朗伯-比尔定律被广泛用作吸收光谱定量分析的基本方程。然而，也观察到了与布格-朗伯-比尔定律的偏差，如化学偏差和光散射效应。虽然已经证明并表明布格-朗伯-比尔定律仅在非常有限的条件下才有效，但针对该定律的分析模型替代方案却很少。基于实验观察，我们提出了一种新颖的模型来解决化学偏差和光散射效应问题。为了测试所提出的模型，使用重铬酸钾溶液以及两种不同浓度和光程长度的微藻悬浮液进行了系统验证。我们提出的模型表现出色，所有测试材料的相关系数（ ）均超过0.995，显著超过布格-朗伯-比尔定律，后者的相关系数低至0.94。我们的结果证实，纯色素溶液的吸光度遵循布格-朗伯-比尔定律，而微藻悬浮液由于光散射效应则不然。我们还表明，这种散射效应会导致光谱常用线性缩放产生巨大偏差，并且我们基于所提出的模型提供了更好的解决方案。这项工作为化学分析尤其是微生物定量分析提供了有力工具，例如生物质或细胞内生物分子的浓度测定。该模型不仅具有高精度，而且简单易行，使其成为现有布格-朗伯-比尔定律的实用替代方案。
