Qualitative Analysis of Amino Acids
Description
This interactive virtual lab lets students identify an unknown amino acid sample by running it through a sequence of nine classic qualitative color tests at a virtual test-tube bench, mirroring standard biochemistry laboratory practice. At each station, students drag the correct reagents onto a test tube (or filter paper strip), apply the appropriate action such as boiling, chilling, vortexing, or drying, and observe the resulting color change, from Ruhemann's purple in the ninhydrin test to the red azo dye of Pauly's diazo test to the black precipitate of the lead sulphide test. Each result is automatically logged to a running notebook table of test, reagents, result, and conclusion, and after completing all nine tests students use the accumulated pattern of positive and negative results to deduce which amino acid, or class of amino acid, their unknown sample contains.
Learning Outcomes
By completing this lab, students will be able to describe the chemical principle behind each qualitative amino acid test, including which functional group or side chain each reagent targets. They will be able to correctly perform the reagent-addition and reaction-condition sequence for tests such as ninhydrin, xanthoproteic acid, Millon's, Pauly's diazo, Hopkins-Cole, Sakaguchi, histidine, lead sulphide, and isatin, and predict the expected color outcome for a positive versus a negative result. Students will be able to distinguish between general amino acid tests (ninhydrin) and group-specific tests that detect aromatic, phenolic, sulphur-containing, guanidine-bearing, or imino amino acid side chains. Finally, students will be able to interpret a pattern of results across multiple tests to logically deduce the identity of an unknown amino acid sample, and explain relevant laboratory safety precautions for handling concentrated acids and reactive reagents used in these tests.