Chiral Analysis by Tandem Mass Spectrometry Using the Kinetic Method, by Polarimetry, and by 1H NMR Spectroscopy

The goal of this laboratory exercise was for students to understand the concept of chirality and how enantiomeric excess (ee) is experimentally determined using the analysis of ibuprofen as an example. Students determined the enantiomeric excess of the analyte by three different instrumental methods: mass spectrometry, nuclear magnetic resonance spectroscopy, and optical polarimetry. This laboratory exercise introduced mass spectrometry into the first-semester organic chemistry curriculum. Further, it allowed the students to compare and contrast the analytical figures of merit for each technique, a topic usually discussed later in chemistry courses. The ee resolution, sensitivity, limits of detection, and required sample preparation were considered. Furthermore, this laboratory experiment taught students how to use the kinetic method for chiral analysis by mass spectrometry, a new technique in a student laboratory exercise. Students' knowledge of how to select the appropriate technique for enantiomeric excess determination was broadened, as knowledge of the general concept of chirality, as seen in their laboratory reports and exit interviews.