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Chemistry LibreTexts

Introduction

Although microchip CE was introduced in 1992,1 and many publications have followed since (as indicated by recent reviews),2-4 such experiments have not yet become a part of the analytical chemistry curriculum. A microchip CE laboratory experiment would provide students valuable exposure to miniaturized methods for chemical analysis, which are growing in importance due to their potential to facilitate rapid assays, while reducing chemical waste generation and reagent consumption. Why has microchip CE not yet become a part of the chemistry laboratory curriculum? The answer is most likely tied to the direct correlation between the separation performance and the cost/fabrication complexity of CE microdevices. At one extreme, expensive and difficult-to-fabricate photolithographically patterned glass microfluidic systems offer the best CE performance and reliability,5,6 while on the other hand, rapidly prototyped and easy-to-make polydimethylsiloxane7-10 microchips offer inferior separation performance and reproducibility. The only published description of an undergraduate microscale CE laboratory experiment, which utilized mechanically patterned glass substrates, also followed this cost/performance correlation (both were low).11 Alternatively, commercial microchip CE instrumentation (e.g., from Agilent) can be used,12 but again, the cost/performance correlation (in this case, high) is a deterrent to large-scale implementation. Importantly, my group has developed polymer microdevice fabrication methods that allow rapid and simple construction of high-performance CE microchips,13-16 thus breaking the cost/performance correlation and providing an ideal platform for a microchip CE laboratory experiment. We anticipate that our development of this experiment will modernize the chemistry laboratory curriculum and enhance the teaching of separations in analytical chemistry courses.

Our focus was to develop a broadly applicable platform for microchip CE experiments in chemistry laboratories, and this work accomplishes two main purposes. First, the microchip CE experiment updates the analytical chemistry laboratory curriculum to include more current techniques. Second, the microchip CE experiment should provide a more in-depth exposure to separations. In this manuscript, we describe the requirements for setting up and carrying out a microchip CE experiment in instrumental analysis laboratories. In addition, we discuss the experimental outcomes from various student groups who have completed this laboratory module. This experiment provides students with valuable experience in the fields of microfluidics and separations, and helps train chemists in the use of microscale methods.