1. Qualitative Tests to Detect Pmtein Qualitative tests simply indicate the presence or absence of a particular substance . You will perform the following two tests on the substances indicated in the tables below . Reagents are at your desks . Samples of amino acids St proteins are on the side bench . a. Ninhydrin Test for Protein : Ninhydrin reacts with the amine group at the end of a peptide chain . It cleaves off the amine , forming ammonia . The ammonia and ninhydrin react to form a violet purple precipitate . The test indicates the presence or absence of peptides. Use the following procedure to test the samples that are listed in the table below. Procedure 1. Add 3 ml of sample to a LARGE test tube . add a scoopful of Sodium Acetate (about the size of a sunower seed) Add 8 drops of Ninhydrin Reagent Boil the contents of the test tube for 3 minutes . Results {II-PkWN + test = purple or violet color - test = no purple color If there is no color change , let the test tube cool to room temperature and check again before recording a negative result _ b. Pauly Test for the amino acids Tyrosine and for I-Iistidine Sulfanilic acid reacts with Tyrosine and Histidine under alkaline conditions to produce a color change. Use the following procedure to test the samples that are listed in the table below