Basal, Lina A., and Kendra R. Evans
Design of undergraduate laboratory experiments to accurately reflect authentic scientific challenges is critical to prepare students for their future careers. Experiments targeted toward the detection of water and soil contaminants are examples of “real-world” laboratory exercises frequently performed as part of the undergraduate instrumental chemistry curriculum. The majority of such experiments use atomic absorption spectroscopy or inductively coupled plasma spectroscopy, both of which are appropriate techniques for analyses of metal contamination in environmental samples. Liquid chromatography-mass spectrometry (LC-MS), however, is one of the most widely-used instruments in chemistry, biology, forensic, and medical research labs, and has also found significant application to environmental monitoring. Thus, experience with LC-MS instrumentation preceding graduation is highly valuable to undergraduate students of the physical sciences. We present progress toward the development of an undergraduate chemistry experiment that employs LC-MS for quantitating over-the-counter and prescription pharmaceuticals, herbicides, and pesticides. The experiment highlights the strengths and limitations of both LC and MS. It also introduces several important principles of LC and MS, including but not limited to chromatographic techniques, separation efficiency, limits of detection, ionization methods, and mass accuracy. The experiment can be strengthened by comparing LC-MS to a complementary technique, gas chromatography-mass spectrometry.