Wen J, Lin Y, Xiang F, Matson D W, Udseth H R, Smith R D
Environmental Molecular Science Laboratory, Pacific Northwest National Laboratory, Richland, WA 99352, USA.
Electrophoresis. 2000 Jan;21(1):191-7. doi: 10.1002/(SICI)1522-2683(20000101)21:1<191::AID-ELPS191>3.0.CO;2-M.
A novel microfabricated device for isoelectric focusing (IEF) incorporating an optimized electrospray ionization (ESI) tip was constructed on polycarbonate plates using laser micromachining. The IEF microchip incorporated a separation channel (50 micro x 30 micro x 16 cm), three fluid connectors, and two buffer reservoirs. Electrical potentials used for IEF focusing and electrospray were applied through platinum electrodes placed in the buffer reservoirs, which were isolated from the separation channel by porous membranes. Direct ESI-mass spectrometry (MS) using electrosprays produced directly from a sharp emitter "tip" on the microchip was evaluated. The results indicated that this design can produce a stable electrospray and that performance was further improved and made more flexible with the assistance of a sheath gas and sheath liquid. Error analysis of the spectral data showed that the standard deviation in signal intensity for an analyte peak was less than approximately 5% over 3 h. The production of stable electrosprays directly from microchip IEF device represents a step towards easily fabricated microanalytical devices. Microchannel IEF separations of protein mixtures were demonstrated for uncoated polycarbonate microchips. Direct microchannel IEF-ESI-MS was demonstrated using the microfabricated chip with an ion-trap mass spectrometer for characterization of protein mixtures.
利用激光微加工技术在聚碳酸酯板上构建了一种新型的用于等电聚焦（IEF）的微加工装置，该装置集成了优化的电喷雾电离（ESI）尖端。IEF微芯片包含一个分离通道（50微米×30微米×16厘米）、三个流体连接器和两个缓冲液储液器。用于IEF聚焦和电喷雾的电势通过置于缓冲液储液器中的铂电极施加，这些电极通过多孔膜与分离通道隔离。对使用微芯片上尖锐发射器“尖端”直接产生的电喷雾进行直接电喷雾质谱（MS）分析进行了评估。结果表明，这种设计能够产生稳定的电喷雾，并且在鞘气和鞘液的辅助下性能得到进一步改善且更加灵活。光谱数据的误差分析表明，在3小时内，分析物峰信号强度的标准偏差小于约5%。直接从微芯片IEF装置产生稳定的电喷雾代表了朝着易于制造的微分析装置迈出的一步。展示了未涂层聚碳酸酯微芯片对蛋白质混合物的微通道IEF分离。使用带有离子阱质谱仪的微加工芯片展示了直接微通道IEF-ESI-MS用于蛋白质混合物的表征。
