Identifying Pharmacopoeial Amino Acids through an Instructive Sequence of Physical, Chemical, and Chromatographic Analyses

The identification of an unknown substance sample can be instructive and exciting training for students on the condition that chemical tests and chromatographic analyses are not uncritical applications of literature prescriptions. Here, we describe a laboratory experience for undergraduate students based on an analytical scheme leading to the identification of an unknown amino acid through a sequence of physical, chemical, and chromatographic tests accomplished according to a previously provided decision tree. Only after differentiating the amino acids for their solubility in water and the pH of their solution/suspension do students apply chemical or HPLC analyses within the resultant amino acids subsets with awareness of the mechanism and the specificity of the reactions and the principles of the HPLC separation. The laboratory experience is designed so that students implement their knowledge of general, organic, and analytical chemistry.