Mass Spectrometry Does Not Need to Be a “Grind”: Plant Secondary Metabolites in Coffee and Black Pepper as a Practical Liquid Chromatography-Tandem Mass Spectrometry (LC-MS/MS) Teaching Tool

Liquid
chromatography-tandem mass spectrometry (LC-MS/MS) is a
powerful analytical technique used in many disciplines. Therefore,
teaching this technique in the undergraduate laboratory should involve
practical data collection in a “real-world” application.
For an upper division plant chemistry course, we developed a laboratory
module of two experiments analyzing plant secondary metabolites in
food and beverage products by LC-MS/MS. In the first, students use
product ion scans and literature references to determine which chlorogenic
acids (phenolic antioxidants), including which isomers, are present
in coffee and hard cider. In the second experiment, students performed
an untargeted analysis of peppercorn extract, examining the MS/MS
fragmentation of the major alkamides (compounds responsible for pepper’s
pungency). Students then selected unknown alkamides, performed product
ion scans, and proposed structures based on the observed fragments
and losses. These experiments emphasize the utility of MS/MS for distinguishing
closely related compounds, for making qualitative comparisons, and
for proposing structures of unknown compounds. Both a pretest/post-test
assessment and laboratory reports were used to assess learning outcomes
related to MS/MS.