Demonstrating Electrophoretic Separation in a Straight Paper Channel Delimited by a Hydrophobic Wax Barrier

A demonstration is described of electrophoretic separation of carmine and sunset yellow with a paper-based device. The channel in the paper device was fabricated by hand with a wax pen. Electrophoretic separation of carmine and sunset yellow was achieved within a few minutes by applying potential on the channel using a simple and inexpensive power supply. This demonstration could not only motivate the students' passion in learning analytical chemistry but also introduce two important analytical techniques (microfluidic paper-based analytical devices and electrophoresis) to the classroom. With further modification and improvement, this demonstration may be suitable for students to perform as a laboratory experiment in the teaching lab.