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Research in Microfluidics 

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Research in Microfluidic Transport at Sandia National Laboratories

On-Chip Chromatography

Chip Electrochromatography(ChEC)

Parallel Separations
Parallel Separations
Packed Channels
Packed Channels

We rely on a number of parallel separations in order to detect molecules of interest.

Reversed-phase capillary electrochromatography (CEC) is an attractive technique for doing chromatography on a planar format. Applications include the separation of small neutral molecules, peptides, and proteins. These separations are relevant to national security issues as well as biomedical and pharmaceutical applications.

Packing channels etched in chips with coated silica beads can be laborious. By using photo-initiated porous polymer monoliths developed at Sandia National Laboratories it is possible to eliminate pressure packing entirely. Because our monoliths are conduct-as -cast, it is possible to replace the buffer with out making any pressure connections. Only electric fields are required to control the flow.

We have demonstrated this technique using isocratic separations of polycyclic aromatic hydrocarbons. Nine out of 13 PAH were resolved in less than 15 minutes in a monolith-filled channel on-chip in a distance of approximately 6 cm.


In order to do more interesting separations, such as proteins, we have demonstrated that it is possible to control two different buffers, one high in acetonitrile, and one high in water, and generate a solvent gradient on-chip in the monolith.

solvent gradient image A rhodamine dye in the aqueous buffer show the gradient clearly.


References

Ngola et al., Porous Polymer Monoliths as Separation Media for CEC Analytical Chemistry; 2001; 73(5); 849-856., Y. Fintschenko, W.-Y. Choi, S. M. Ngola, T. J. Shepodd, Fresenius Journal 371 (2001) 174 .

For Further Information Contact: Malin Young