Electrospray ionization mass spectrometry (ESI-MS) and matrix-assisted laser desorption ionization mass spectrometry (MALDI-MS) have found increasing application in the analysis of biological samples. Using these techniques to solve problems in analytical chemistry should be an essential component of the training of undergraduate chemists. We present an experiment that teaches students how to prepare and analyze samples both qualitatively and quantitatively using modern mass spectrometric techniques. Students use ESI-MS and MALDI-MS to analyze phospholipids and mixtures of fatty acids, including those from soybean extracts. Changes in the mixtures upon ozonolysis are also investigated. This laboratory is suitable for upper-level university students enrolled in analytical chemistry or instrumental analysis classes. This experiment combines analytical chemistry with organic chemistry and biochemistry, a situation that students will encounter in their future careers as chemists. (Contains 5 figures and 1 table.)