Department of Chemistry, College of Idaho, 2112 Cleveland Blvd, Caldwell, Idaho 83605, United States.
Pacific Northwest National Laboratory, 902 Battelle Boulevard, Richland, Washington 99352, United States.
Anal Chem. 2021 Jan 26;93(3):1643-1651. doi: 10.1021/acs.analchem.0c04225. Epub 2020 Dec 18.
Microfluidics have many potential applications including characterization of chemical processes on a reduced scale, spanning the study of reaction kinetics using on-chip liquid-liquid extractions, sample pretreatment to simplify off-chip analysis, and for portable spectroscopic analyses. The use of characterization of process streams from laboratory-scale and microscale experiments on the same chemical system can provide comprehensive understanding and in-depth analysis of any similarities or differences between process conditions at different scales. A well-characterized extraction of Nd(NO) from an aqueous phase of varying NO concentration with tributyl phosphate (TBP) in dodecane was the focus of this microscale study and was compared to an earlier laboratory-scale study utilizing counter current extraction equipment. Here, we verify that this same extraction process can be followed on the microscale using spectroscopic methods adapted for microfluidic measurement. Concentration of Nd (based on UV-vis) and nitrate (based on Raman) was chemometrically measured during the flow experiment, and resulting data were used to determine the distribution ratio for Nd. Extraction distributions measured on the microscale were compared favorably with those determined on the laboratory scale in the earlier study. Both micro-Raman and micro-UV-vis spectroscopy can be used to determine fundamental parameters with significantly reduced sample size as compared to traditional laboratory-scale approaches. This leads naturally to time, cost, and waste reductions.
微流控技术有许多潜在的应用，包括在较小的规模上对化学过程进行表征，涵盖使用芯片上的液-液萃取研究反应动力学、简化离芯片分析的样品预处理，以及用于便携式光谱分析。在同一化学体系中，从实验室规模和微尺度实验对过程流进行表征，可以提供对不同尺度下工艺条件之间任何相似性或差异性的全面理解和深入分析。本微尺度研究的重点是用三丁基磷酸酯（TBP）在正十二烷中从不同硝酸浓度的水相中很好地萃取钕（NO），并与早期利用逆流萃取设备的实验室规模研究进行了比较。在这里，我们通过为微流测量而改编的光谱方法，验证了可以在微尺度上遵循相同的萃取过程。在流动实验过程中，对基于 UV-vis 的 Nd 浓度和基于 Raman 的硝酸盐浓度进行了化学计量测量，并且使用所得到的数据确定了 Nd 的分配比。在微尺度上测量的萃取分布与在早期研究中在实验室规模上确定的分布相吻合。与传统的实验室规模方法相比，微拉曼和微 UV-vis 光谱学都可以用于确定具有显著减少的样品量的基本参数。这自然会导致时间、成本和废物的减少。
