Expt.1: Qualitative Tests for Carbohydrates and Amino Acids BCH 2720 IBM Expt.1: Qualitative Tests for Carbohydrates and Amino Acids

1a: Carbohydrates Characterization Molisch’s Test : carbohydrate Barfoed’s Test : Monosaccharides and Oligosaccharides Seliwanoff Test : Differentiation of Ketose from Aldose Iodine Test : Cellulose, Starch, Dextrin

Experiment 1 I. Principle Qualitative Tests for Carbohydrates 1. Molisch’s Test - test for carbohydrates a-naphthol Pentose/ Hexose conc.H2SO4 Furfural 5-hydroxymethyl furfural (Purple complex) - H2O 2. Barfoed’s Test - test for reducing sugars - test for distinguishing monosaccharides and disaccharides Slightly acidic Reducing sugar + 2Cu2+ 2Cu+ + oxidized sugar Cu2O (brick red ppt) 3. Seliwanoff Test - test for distinguishing ketose from aldose resorcinol conc. HCl 5-hydromethyl furfural Ketohexose red complex dehydration 4. Iodine Test - test for starch Starch + I2 starch - I2 complex (deep blue)

Barfoed's Test RCHO  +  2Cu2+  +  2H2O ----->   RCOOH  +  Cu2O  +  4H+ Barfoed's reagent reacts with monosaccharides to produce cuprous oxide at a faster rate than disaccharides do

Monosaccharide & Disaccharides Glucose Fructose Disaccharides  Maltose Lactose Sucrose

Ketone & Adehyde

Polysaccharide Starch Glycogen Cellulose

Molisch’s Test Test for carbohydrate materials Using 2 ml of test solution in a test tube, add 50 l of the  1-naphthol, mix and then allow 1 ml of conc. Sulphuric acid to flow down the side of the inclined tube to layer under the mixture. Note the colour at the junction.

Barfoed’s Test Test for Monosaccharides and Oligosaccharides Using 0.5 ml of test solution, mix with 2.5 ml of Barfoed’s solution in a test tube and boil for 15 minutes. Note the time of first sign of precipitate appears. After 15 minutes, cool it down and observe the amount of precipitate in each tube.

Seliwanoff Test Test for Differentiation of Ketose from Aldose Add 0.5 ml of the test solution to 2.5 ml of the Seliwanoff’s reagent. Place the tubes in boiling water and note the results and continue heating, observe the colour change at 1 minute interval for 5 minutes.

Iodine Test Test for Cellulose, Starch, Dextrin Add 50 l of aqueous iodine solution to 4 ml test solution. Record the colours observed. Then heat the tubes 5 mins, record the effect on the colours, cool the tube again and note the effect on the colours.

1b. General Properties of amino acids The Ninhydrin Reaction: oxidising agent (It reacts with -amino acids to produce a purple coloured compound to measure the amount of -amino acid in a sample.)

The Ninhydrin Reaction Mix 1 ml of test solution and 50 l of ninhydrin reagent in a test tube. Boil for 5 minutes and observe the colour change. (Tyrosine, Tryptophan & Proline) serial dilution of glycine

Ruhemann’s Pruple

Lab Report Control is Water Date of Experiment : 24 Jan 2006 (Tue) Date of Submission: 10 Feb 2006 (Before 5:00p.m.) (Fri) Demonstrator in-charge: Edmond Room no. : MMW 612A

Lab Report (Con’t) Title and Introduction - 0.5 M Results – 2.5 M Discussion – 5 M Conclusion and Recommendation – 1.5 M Reference – 0.5 M