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

Abstract

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 "realworld" 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.

Familiarize Students with Direct MS Analysis Methods: Localization of Components in Citrus Peel by Induced Electrospray Ionization

“…Students can usually gain ESI-MS trainings through three main ways: (1) theoretical and laboratory courses of MS for senior undergraduate or graduate students; (2) MS analysis facilities in the university; and (3) research projects that students participate in. It should be noted that many of the above trainings prefer to introduce well-established ESI-MS methods to students, such as flow injection-based ESI-MS for peptide, protein, and host–guest complex analysis and liquid chromatography ESI-MS (LC-ESI-MS) for metabolites analysis in complicate biological matrix, − etc. Although these trainings can provide stable MS information about samples, they may show limitations in the cases of real-time reaction monitoring, biological in situ analysis, etc., where direct sampling and analysis is required.…”