A polymeric microfluidic device for separation of small molecule

We have used an embossed plastic microfluidic system for the electrophoretic separation of relatively small molecules followed by electrospray ionization of the analytes. The separation of dyes has been also visualized in microfluidic systems. A lithographically produced silicon master was used to emboss channels in ZEONOR 1020R plastic. An oxygen plasma was used to convert the plastic channel surface from hydrophobic to hydrophilic characteristics for the separation of molecules in aqueous solution. The channels were sealed by thermal bonding of a cover piece of the same plastic material. The microfluidic device used for mass spectrometry had a separation channel 60 μm wide, 20 μm deep and 3.5 cm long. The channel exit terminated at the edge to couple to a microsprayer for electrospray ionization. A related microfluidic device for electrophoretic separation and fluorescence detection had a separation channel 50 μm wide, 20 μm deep and 3.5 cm long. This was used to separate two dye molecules, Rhodamine B and Texas Red. The volume of sample plug injected into separation channel through a double T junction electrokinetically for mass spectrometry device was calculated to be 2.0 nl and samples were separated within 10 seconds with an applied electric field of 1200 V/cm. The sample volume injected through cross junction for fluorescence detection device was calculated to be 1.2 nl and two dyes were separated within 8 second with the application of electric field 300 V/cm.