Simultaneous absorption of UV-vis and circular dichroism to measure enantiomeric concentrations of praziquantel under nonlinear conditions
Simultaneous absorption of UV-vis and circular dichroism to measure enantiomeric concentrations of praziquantel under nonlinear conditions
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DOI：
10.1016/j.saa.2020.118645
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发表时间：
2020-11-05
影响因子：
4.4
通讯作者：
Barreto Jr, A. G.
中科院分区：
文献类型：
--
作者：
Cunha, F. C.;de Holanda, R. C.;Barreto Jr, A. G.
Beer-Lambert-Bouguer定律是一种极限情况，因此，当存在非线性现象时，描述吸收信号与对映体浓度之间的关系是不适用的。本工作使用手性检测器(CD-2095 JASCO)设备同时测量了含有不同组成的吡喹酮对映体的紫外可见光谱和圆二色谱信号。使用留一法交叉验证(LOOCV)对模型进行了校准(参数估计)和验证。与纯溶液相比，UV-Vis和CD信号在混合物中的吸收有所不同，表明吸收信号与混合流中对映体浓度之间存在非线性关系。测试每个信号(UV-Vis和CD)的经验数学关系，并使用每个对映体浓度(MSEL和MSED)的均方误差(MSE)度量来评估这对方程，并选择MSEt(=MSEL+MSED)度量最小的一对方程。可信区间分析有助于找到比所选方程更简单的方程。低浓度的L-PZQ混合物具有较高的非线性。开发的方法允许选择经验模型，在广泛的浓度范围内给出良好的预测，例如，这对于监测和自动控制目的是至关重要的。(C)2020爱思唯尔B.V.保留所有权利。
Beer-Lambert-Bouguer law is for a limiting case and, therefore, it is not useful to describe the relationship between absorption signal and enantiomer concentration in a stream when there are nonlinear phenomena present. In this work, the Chiral Detector (CD-2095 JASCO) equipment was used to measure simultaneously the UV-Vis and circular dichroism (CD) signals of a stream with different compositions of praziquantel enantiomers. The tested models were calibrated (parameter estimation) and validated using the Leave-One-Out Cross Validation (LOOCV) method. Both UV-vis and CD signals were absorbed differently in mixtures in comparison to pure solutions, indicating a nonlinear relationship between the absorbed signal and the enantiomer concentration in a mixture stream. Empirical mathematical relationships were tested for each signal (UV-vis and CD) and the pair of equations was evaluated using the Mean Square Error (MSE) metric for each enantiomer concentration (MSEL and MSED) and the pair of equations with the smallest MSEt (=MSEL + MSED) metric was chosen. Confidence interval analysis helped to find even simpler equations in comparison to the chosen ones. Higher nonlinearity was observed for a mixture with low L-PZQ concentration. The developed methodology allowed the choice of an empiric model to give good predictions in a wide range of concentration, what is of utmost importance for monitoring and automatic control purposes, for instance. (C) 2020 Elsevier B.V. All rights reserved.