Capillary electrophoresis is an important analytical separation method used to study a wide variety of samples, including those of biological origin. Capillary electrophoresis may be covered in the classroom, especially in advanced analytical courses, and while many students are exposed to gel electrophoresis in biology or biochemistry laboratories, capillary electrophoresis is not as commonly found in undergraduate lab curricula. Published lab experiments that incorporate capillary electrophoresis include the analysis of caffeine in beverages and cations in water samples but not of more biological samples such as a peptide mixture. This paper introduces a peptide separation based on capillary zone electrophoresis that is both qualitative and quantitative. It describes the separation of four small peptides where two of the analytes have similar migration times, forcing students to think about how they can best identify which peak corresponds to which analyte, while exposing them to a bioanalytical application of capillary electrophoresis.