Preparation and Characterization of a Monolithic Column for use in HPLC: An Undergraduate Laboratory Experiment

The high-performance liquid chromatography (HPLC) experiment, most often done in the undergraduate analytical instrumentation laboratory course, generally illustrates reversed-phase chromatography using a commercial C18 silica column. To avoid the expense of periodic column replacement and introduce a choice of columns with different stationary phases, we have developed an experiment in which students prepare and test a polymer-based monolithic column. The 10 or 15 cm monolithic column is prepared using 1/8 in. o.d. × 2.3 mm i.d. poly(ether ether ketone) or PEEK tubing. The reaction is accomplished thermally at 60 °C for several hours by polymerization of butyl methacrylate cross-linked with ethylene glycol dimethacrylate in a porogen system consisting of 1,4-butanediol, 1-propanol, and water. Using toluene and naphthalene as analytes, profiles of retention factor as a function of methanol have been shown. A study of essential nutrients can be accomplished by using an ion-pairing reagent to separate thiamine from riboflavin. In addition, plate count and van Deemter plots can be done to determine column efficiency. The experiment can be designed to be completed over a 1 to 3 week period of time. Exposure to polymer chemistry, often not a part of the undergraduate laboratory curriculum, is an additional important aspect of this experiment.