Vahey P G, Park S H, Marquardt B J, Xia Y, Burgess L W, Synovec R E
Department of Chemistry, Center for Process Analytical Chemistry, Box 351700, University of Washington, Seattle, WA 98195, USA.
Talanta. 2000 May 5;51(6):1205-12. doi: 10.1016/s0039-9140(00)00311-8.
A rapid and low-cost means of developing a working prototype for a positive-displacement driven open tubular liquid chromatography (OTLC) analyzer is demonstrated. A novel flow programming and injection strategy was developed and implemented using soft lithography, and evaluated in terms of chromatographic band broadening and efficiency. A separation of two food dyes served as the model sample system. Sample and mobile phase flowed continuously by positive displacement through the OTLC analyzer. Rectangular channels, of dimensions 10 mum deep by 100 mum wide, were micro-fabricated in poly-dimethylsiloxane (PDMS), with the separation portion 6.6 cm long. Using a novel flow programming method, in contrast to electroosmotic flow, sample injection volumes from 0.5 to 10 nl were made in real-time. Band broadening increased substantially for injection volumes over 1 nl. Although underivatized PDMS proved to be a sub-optimal stationary phase, plate heights, H, of 12 mum were experimentally achieved for an unretained analyte with the rectangular channel resulting in a reduced plate height, h, of 1.2. Chromatographic efficiency of the unretained analyte followed the model of an OTLC system limited by mass-transfer in the mobile phase. Flow rates from 6 nl min(-1) up to 200 nl min(-1) were tested, and van Deemter plots confirmed plate heights were optimum at 6 nl min(-1) over the tested flow rate range. Thus, the best separation efficiency, N of 5500 for the 6.6 cm length separation channel, was achieved at the minimum flow rate through the column of 6 nl min(-1), or 3 ml year(-1). This analyzer is a low-cost sampling and chemical analysis tool that is intended to complement micro-fabricated electrophoretic and related separation devices.
本文展示了一种快速且低成本的方法，用于开发一种用于正位移驱动的开管液相色谱（OTLC）分析仪的工作原型。利用软光刻技术开发并实施了一种新颖的流动编程和进样策略，并从色谱峰展宽和效率方面进行了评估。以两种食用色素的分离作为模型样品系统。样品和流动相通过正位移连续流经OTLC分析仪。在聚二甲基硅氧烷（PDMS）中微加工出深度为10μm、宽度为100μm的矩形通道，分离部分长6.6cm。与电渗流不同，使用一种新颖的流动编程方法可实时进样0.5至10nl的样品。进样体积超过1nl时，峰展宽显著增加。尽管未衍生化的PDMS被证明是次优固定相，但对于未保留的分析物，通过矩形通道实验测得的板高H为12μm，折合板高h为1.2。未保留分析物的色谱效率遵循受流动相传质限制的OTLC系统模型。测试了6nl min⁻¹至200nl min⁻¹的流速，范德姆特曲线证实，在测试的流速范围内，流速为6nl min⁻¹时板高最佳。因此，在通过柱的最低流速6nl min⁻¹（即3ml year⁻¹）下，6.6cm长的分离通道实现了最佳分离效率，理论塔板数N为5500。该分析仪是一种低成本的采样和化学分析工具，旨在补充微加工的电泳及相关分离装置。
