An Organic Chemistry Lab Exercise for Isolating, Derivatizing, and Analyzing Fatty Acid Mixtures from Culinary Fats and Oils

This capstone-style undergraduate organic chemistry laboratory exercise has three main goals: to illustrate interesting and relevant examples of substitution-at-carbonyl reactions, to provide a platform for learning about modern liquid chromatography/mass spectroscopy (LC/MS) analysis, and to provide an opportunity for students to practice analyzing mass spectrometry and chromatography data. In this two-period lab exercise, students first use a hydroxide-promoted hydrolysis reaction to isolate fatty acid mixtures from various common food sources, and then use a carbodiimide-promoted amide-forming reaction to synthesize derivatives of those fatty acids that are ideal for LC/MS analysis. Depending on the size of the class and available facilities, the students may be able to each collect LC/MS data of their derivative mixtures, or data from a subset of the samples may be collected as a demonstration, or the LC/MS instrument can simply be discussed and representative data (provided herein) can be distributed to the students. (Access to an LC/MS instrument is not required to do this lab.) The students then have the opportunity to interpret the LC/MS data and compare the fatty acid mixtures that are found in the various fats and oils that were used as starting materials. This lab experience aims to promote critical thinking through data analysis, and to connect organic chemistry to relevant nutritional topics in a way that engages students and sparks their interest in chemistry.