Chromatography on a Chip

Q. He, C. Pang, Y.-C. Tai, T.D. Lee, Ion liquid chromatography on-a- chip with beads-packed parylene column. Proceedings of the 17th IEEE International Conference on Micro Electro Mechanical Systems (MEMS 2004). Maastricht, The Netherlands, Jan 25-29 (2004). 

As mentioned, there are numerous devices that can perform chromatography on a chip. Figure 7.1 gives an impression of how such a device can look like. 

Figure 7.1 Chromatography on a chip device. Through differing power settings, liquid in the capillaries of the chip can be transported between the various inlet and waste connections. In this way, the sample can be...

Packing the open channels with functionalized particles, as in conventional liquid chromatography, is challenging due to reproducibihty issues and difficult immobilization of the particles. However, at present, there are excellent commercially available chromatography on a chip devices with columns slurry-packed with a great variety of stationary phases. 

In order to produce a robust flow for chromatography on a chip, and which is in the low nanoliter per minute range, several approaches are possible. Flow is either produced by pressure-driven devices (referred to as top-down systems) or by electroosmosis-driven devices (referred to as bottom-up systems). 

Lab-on-a-chip/high-performance liquid chromatography 2005 LOC/HPLC 215 Collins, 13.4... 

Q. He, Integrated nano liquid chromatography system on a chip, Ph.D. thesis, California Institute of Technology, Pasadena, CA, June 21 (2005). 

Wheeler, A., Morishima, K., Kirby, B., Leach, A., Zare, R.N., CATH.a neuron cell analysis on a chip with micellar electrokinetic chromatography. Micro Total Analysis Systems, Proceedings 5th iTAS Symposium, Monterey, CA, Oct. 21-25, 2001, 311-312. 

These small devices have been used in a variety of ways. Liquid chromatography (LC) on-chip approaches are well represented in the literature (45,46). These chips have also been used to study the membrane proteome (47) and protein-protein interaction via fluorescence resonance energy transfer (48). Further examples of technology miniaturization can be found in journals dedicated to the on-chip methodology (i.e., Lab-on-a-Chip). 

Improvement in LC-MS and LC-MS/MS analysis throughput has been reported by the use of monolithic silica columns to increase the speed of chromatography separation [156-158]. The substimtion of an SFC front end to MS in lieu of HPLC has been a growing trend in compound library analysis. It is possible that the use of SFC-MS will be extended to in vitro and in vivo evaluation of library compounds such as ADME and DMPK. CE-MS has not been widely used in the analysis of combinatorial libraries. To date, the application of CE-MS has been frequently in the analysis of mixture-component libraries derived from split synthesis and in the affinity screening of libraries through ACE. However, with the miniaturization of biological screening in the lab-on-a-chip format, CE-MS may find renewed interest... 

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