The content of the flavonolignan mixture silymarin and its individual components (silichristin, silidianin, silibinin A, silibinin B, isosilibinin A, and isosilibinin B) in whole and milled milk thistle seeds (Silybi mariani fructus) was analyzed with near-infrared spectroscopy. The analytical performance of one benchtop and two handheld near-infrared spectrometers was compared. Reference analysis was performed with HPLC following a Soxhlet extraction (European Pharmacopoeia) and a more resource-efficient ultrasonic extraction. The reliability of near-infrared spectral analysis determined through partial least squares regression models constructed independently for the spectral datasets obtained by the three spectrometers was as follows. The benchtop device NIRFlex N-500 performed the best both for milled and whole seeds with a root mean square error of CV between 0.01 and 0.17%. The handheld spectrometer MicroNIR 2200 as well as the microPHAZIR provided a similar performance (root mean square error of CV between 0.01 and 0.18% and between 0.01 and 0.23%, respectively). We carried out quantum chemical simulation of near-infrared spectra of silichristin, silidianin, silibinin, and isosilibinin for interpretation of the results of spectral analysis. This provided understanding of the absorption regions meaningful for the calibration. Further, it helped to better separate how the chemical and physical properties of the samples affect the analysis. While the study demonstrated that milling of samples slightly improves the performance, it was deemed to be critical only for the analysis carried out with the microPHAZIR. This study evidenced that rapid and nondestructive quantification of silymarin and individual flavonolignans is possible with miniaturized near-infrared spectroscopy in whole milk thistle seeds.

中文翻译：

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水飞蓟中水飞蓟素的定量分析：挑战台式与手持式 NIR 光谱仪对整粒种子的分析性能

用近红外光谱分析了整个和磨碎的水飞蓟种子 (Silybi mariani fructus) 中黄酮木脂素混合物水飞蓟素及其单个成分（水飞蓟素、水飞蓟素、水飞蓟宾 A、水飞蓟宾 B、异水飞蓟素 A 和异水飞蓟宾 B）的含量。比较了一台台式和两台手持式近红外光谱仪的分析性能。在索氏提取法（欧洲药典）和资源效率更高的超声提取法之后，使用 HPLC 进行参考分析。通过对三个光谱仪获得的光谱数据集独立构建的偏最小二乘回归模型确定的近红外光谱分析的可靠性如下。台式设备 NIRFlex N-500 对碾磨过的种子和整粒种子均表现最佳，CV 的均方根误差在 0.01% 到 0.17% 之间。手持式光谱仪 MicroNIR 2200 和 microPHAZIR 提供了相似的性能（CV 的均方根误差分别介于 0.01 和 0.18% 之间以及介于 0.01 和 0.23% 之间）。我们对水飞蓟素、水飞蓟素、水飞蓟宾和异水飞蓟宾的近红外光谱进行了量子化学模拟，以解释光谱分析结果。这提供了对对校准有意义的吸收区域的理解。此外，它有助于更​​好地分离样品的化学和物理特性如何影响分析。虽然研究表明样品的研磨略微提高了性能，它被认为仅对使用 microPHAZIR 进行的分析至关重要。该研究证明，在全脂蓟种子中使用小型化近红外光谱可以快速且无损地定量水飞蓟素和单个黄酮木脂素。