Department of Chemistry, The University of Hong Kong, Hong Kong, Hong Kong SAR, P R China.
Electrophoresis. 2010 Sep;31(18):3044-52. doi: 10.1002/elps.201000297.
To meet the need for onsite monitoring of urine anions, a microfluidic chip-capillary electrophoresis device was designed, fabricated and tested to extend the upper CE working range for an enhancement up to 500 fold (100 fold for sample dilution and 5 folds for CE injection) in order to analyze highly variable anionic metabolites in urine samples. Capillaries were embedded between two PMMA plates with laser-fabricated microchannel patterns to produce the microfluidic chip-capillary electrophoresis to perform standard/sample dilution and CE injection with adjustable dilution ratios. A circular ferrofluid valve was incorporated on-chip to perform cleanup and conditioning, mixing and dilution, injection and CE separation. Under optimized conditions, a complete assay for four samples can be achieved within an hour for 15 anions commonly found in urines. Satisfactory working ranges (0.005-500 mM) and low detection limits (0.5-6.5 μM based on S/N =2) are obtained with satisfactory repeatability (RSD, n=5) 0.52-0.87% and 4.1-6.5% for migration time and peak area, respectively. The working ranges with two orders adjustable upper extension are adequate to cover all analytes concentrations commonly found in human urine samples. The device fabricated shows sufficiently large experimentally verifiable enhancement factor to meet the application requirements. Its reliability was established by more than 94% recoveries of spiked standards and agreeable results from parallel method comparison with conventional ion chromatography method. The extension of the upper CE working range enables flexible onsite dilution on demand, a quick turn-around of results, and a low-cost device suitable for bedside monitoring of patients under critical conditions for metabolic disorders.
为了满足尿液阴离子现场监测的需求，设计、制造和测试了一种微流控芯片-毛细管电泳装置，将 CE 的工作范围上限扩展了 500 倍（样品稀释扩展了 100 倍，CE 进样扩展了 5 倍），从而能够分析尿液样品中高度变化的阴离子代谢物。毛细管嵌入在两块带有激光加工微通道图案的 PMMA 板之间，形成微流控芯片-毛细管电泳，以执行标准/样品稀释和 CE 进样，并具有可调节的稀释比。在芯片上集成了一个圆形铁磁流体阀，用于进行清洗和调理、混合和稀释、进样和 CE 分离。在优化条件下，对于 15 种常见的尿液阴离子，四种样品的完整分析可以在 1 小时内完成。获得了令人满意的工作范围（0.005-500 mM）和低检测限（基于 S/N = 2，0.5-6.5 μM），迁移时间和峰面积的重复性分别为 0.52-0.87%和 4.1-6.5%。可调上延两个数量级的工作范围足以覆盖人体尿液样品中常见的所有分析物浓度。所制造的设备具有足够大的实验验证增强因子，以满足应用要求。通过对加标标准品的回收率超过 94%，以及与传统离子色谱法的平行方法比较得到可接受的结果，证明了其可靠性。CE 工作范围上限的扩展使得能够按需进行灵活的现场稀释，快速获得结果，并且是一种低成本的设备，适用于代谢紊乱患者的床边监测。
