Li Yan, Dvořák Miloš, Nesterenko Pavel N, Stanley Roger, Nuchtavorn Nantana, Krčmová Lenka Kujovská, Aufartová Jana, Macka Mirek
School of Physical Sciences and Australian Centre for Research on Separation Science (ACROSS), University of Tasmania, Private Bag 75, Hobart 7001, Australia.
School of Physical Sciences and Australian Centre for Research on Separation Science (ACROSS), University of Tasmania, Private Bag 75, Hobart 7001, Australia; Department of Food Chemistry and Biotechnology, Faculty of Chemistry, Brno University of Technology, Brno, Czech Republic.
Anal Chim Acta. 2015 Oct 8;896:166-76. doi: 10.1016/j.aca.2015.09.015. Epub 2015 Sep 25.
Trends towards portable analytical instrumentation of the last decades have not been equally reflected in developments of portable liquid chromatography (LC) instrumentation for rapid on-site measurements. A miniaturised medium pressure capillary LC (MPLC) system with gradient elution capability has been designed based on a flexible modular microfluidic system using primarily off-the-shelf low cost components to ensure wide accessibility to other analysts. The microfluidic platform was assembled on a breadboard and contained microsyringe pumps and switch valves, complemented with an injection valve and on-capillary detectors, all controlled by a PC. Four miniaturised microsyringe pumps, with 5, 20 and 100 μL syringe volume options, formed the basis of the pumping system. Two pairs of pumps were used for each mobile phase to create gradient elution capability. The two microsyringe pumps in each pairs were linked by two electrically operated microfluidic switching valves and both pairs of pumps were connected through a zero void volume cross-connector, thus providing a low hold-up volume for gradient formation. Sample was injected by a 20 nL nano-LC sampling valve, directly connected to a 18 cm long 100 μm i.d. Chromolith CapRod RP-18 monolithic capillary column. On-capillary LED-based UV-vis photometric detection was conducted through a piece of equal diameter fused silica capillary connected after the column. The performance of the portable LC system was evaluated theoretically and experimentally, including the maximum operating pressure, gradient mixing performance, and the performance of the detectors. The 5 μL microsyringe pump offered the best performance, with typical maximum operating pressures up to 11.4 ± 0.4 MPa (water) and gradient pumping repeatability of between 4 and 9% for gradients between 0.10% s(-1) and 0.33% s(-1). Test analytes of charged and uncharged dyes and pharmaceuticals of varying hydrophobicity showed typical RSD values of 0.7-1.4% and 3.3-4.8% in isocratic mode and 1.2-4.6% and 3.2-6.4% in gradient mode, respectively for retention time and peak area repeatability.
在过去几十年中，便携式分析仪器的发展趋势在用于快速现场测量的便携式液相色谱（LC）仪器的发展中并未得到同等体现。基于一种灵活的模块化微流控系统设计了一种具有梯度洗脱能力的小型化中压毛细管LC（MPLC）系统，该系统主要使用现成的低成本组件，以确保其他分析人员能够广泛使用。微流控平台组装在实验板上，包含微型注射器泵和切换阀，并配有进样阀和毛细管上的检测器，所有这些均由一台计算机控制。四个微型注射器泵，注射器体积有5、20和100μL可选，构成了泵送系统的基础。每一种流动相使用两对泵以实现梯度洗脱能力。每对中的两个微型注射器泵通过两个电动微流控切换阀相连，且两对泵通过一个零死体积交叉连接器连接，从而为梯度形成提供了低滞留体积。样品由一个20 nL的纳米LC进样阀进样，该进样阀直接连接到一根18 cm长、内径100μm的Chromolith CapRod RP - 18整体式毛细管柱。基于毛细管上的LED紫外 - 可见光度检测通过一根与柱后相连的等直径熔融石英毛细管进行。对该便携式LC系统的性能进行了理论和实验评估，包括最大操作压力、梯度混合性能以及检测器的性能。5μL微型注射器泵表现最佳，典型的最大操作压力高达11.4±0.4 MPa（水），对于0.10%s⁻¹至0.33%s⁻¹的梯度，梯度泵送重复性在4%至9%之间。不同疏水性的带电和不带电染料及药物测试分析物在等度模式下保留时间和峰面积重复性的典型相对标准偏差（RSD）值分别为0.7 - 1.4%和3.3 - 4.8%，在梯度模式下分别为1.2 - 4.6%和3.2 - 6.4%。
