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Abstract：
The Bouguer-Lambert-Beer (BLB) law serves as the fundamental basis for the spectrophotometric determination of pigment content in microalgae. Although it has been observed that the applicability of the BLB law is compromised by the light scattering effect in microalgae suspensions, in-depth research concerning the relationship between the light scattering effect and the accuracy of spectrophotometric pigment determination remains scarce. We hypothesized that (1) the precision of spectrophotometric pigment content determination using the BLB law would diminish with increasing nonlinearity of absorbance, and (2) employing the modified version of the BLB (mBLB) law would yield superior performance. To assess our hypotheses, we cultivated Phaeodactylum tricornutum under varying illumination conditions and nitrogen supplies in controlled indoor experiments, resulting in suspensions with diverse pigment contents. Subsequently, P. tricornutum samples were diluted into subsamples, and spectral measurements were conducted using different combinations of biomass concentrations and path lengths. This was carried out to assess the applicability of the BLB law and the nonlinearity of absorbance. The chlorophyll a and fucoxanthin contents in the samples were analyzed via high-performance liquid chromatography (HPLC) and subsequently used in our modeling. Our findings confirm our hypotheses, showing that the modified BLB law outperforms the original BLB law in terms of the normalized root mean square error (NRMSE): 6.3% for chlorophyll a and 5.8% for fucoxanthin, compared to 8.5% and 7.9%, respectively.
摘要：
Bouguer-Lambert-Beer（BLB）定律是分光光度法测定微藻中色素含量的基本依据。尽管已经观察到BLB定律的适用性受到微藻悬浮液中的光散射效应的损害，关于光散射效应与分光光度法测定颜料的准确性之间关系的深入研究仍然很少。我们假设（1）使用BLB定律测定分光光度颜料含量的精度会随着吸光度非线性的增加而降低，(2)采用BLB(mBLB)定律的修改版本将产生优异的性能。为了评估我们的假设，在受控的室内实验中，我们在不同的光照条件和氮素供应下培养了三角Phaeodactylum，导致具有不同颜料含量的悬浮液。随后，将Trigornutum样本稀释成子样本，使用生物质浓度和路径长度的不同组合进行光谱测量。进行此操作以评估BLB定律的适用性和吸光度的非线性。通过高效液相色谱（HPLC）分析样品中的叶绿素a和岩藻黄质含量，随后将其用于我们的建模中。我们的发现证实了我们的假设,表明修改后的BLB定律在归一化均方根误差（NRMSE）方面优于原始BLB定律：叶绿素a为6.3％，岩藻黄质为5.8％，与8.5%和7.9%相比，分别。
