Experiment I: Carbohydrate Analysis

EXPERIMENT I CARBOHYDRATE ANALYSIS 1.Molisch test Molisch's reagent is very effective for testing dehydrating compounds by concentrated sulfuric acid into furfural compounds or substituted furfural compounds, such as hydroxymethyl-furfural. The color that occurs is caused by condensation of furfural or its derivatives with -- Naphthol produces a reddish purple compound. Apart from that, furfural can condenses with various phenolic or amine compounds to give colored compound derivatives. This test is a general test for carbohydrates though the results are not a reaction specific to carbohydrates. Negative results is a clear indication of the absence of carbohydrates. Materials and Reagents : - 1% Glucose Solution - 1% Fructose Solution - 1% Sucrose Solution - 1% Lactose Solution - 1% Maltose Solution - Starch Solution - Molisch's reagent (5% solution of --naphthol in 95% alcohol) - H2SO4Concentrated Ways of working : - Into the test tube, add 5 mL of experimental material and 2-3 drops of reagent Molisch, stir well. - Add slowly through the tube wall 3 mL of concentrated sulfuric acid. Note the color that occurs at the solution boundary. Question : 1. What color is visible between the surfaces of the two solutions? 2. Why do many proteins also give a positive Molisch test? 2. Benedict's Test Benedict's test is based on Cu reduction2+to Cu+. Copper solutions in an alkaline state when reduced by carbohydrates that have an aldehyde group or free ketones will form cuprous oxide (Cu2O) the red one brick. Disaccharides, such as maltose and lactose can reduce Cu2+because it has free ketone groups. In the reduction process in an alkaline environment, substances are usually added complexing agent, such as citrate to prevent CuCO deposition3in solution Sodium carbonate is present in Benedict's reagent. Benedict's test can also be used to estimate the concentration of free carbohydrates due to varying carbohydrate concentrations will provide different color intensities. Reactor : - Benedict's Reagent: Mix 173 grams of sodium citrate and 100 grams of Na2CO3anhydrous in approximately 800 mL of water, stir, then strain. Then add 17.3 grams of CuSO4 which has been dissolved in 100 mL of distilled water. Next the total volume is created to 1 L with distilled water. - 0.1 M galactose: dissolve 18 grams of galactose in 1 L of water. - 0.1 M fructose: dissolve 18 grams of fructose in 1 L of water. - 0.1 M glucose solution, 0.1 M sucrose solution, and 1% starch solution. Procedure: 1. Add 2-3 drops of glucose solution to the test tube containing 1-2 mL of Benedict's reagent, then shaken. Place the test tube into the water bath Boil for 5 minutes, let cool, observe the color change. Formation green, yellow or red precipitate indicates a positive reaction. 1. Carry out the experiment stage (1) for a solution of 0.1 M galactose, maltose, sucrose, fructose and 1% starch solution. 2. Repeat the experiment step (1) for a solution of 0.1 M glucose diluted 2 times, 10 times, 50 times, and 100 times. What are the results of this dilution? Question : 1. What is the lowest carbohydrate level that can still be observed with the test Benedict? 2. What compounds besides copper can be reduced? What are the various functions What are the ingredients in Benedict's reagent? 3.GLUCOSE IN URINE The presence of glucose in the urine can be checked using the technique based on the above the property of glucose which can reduce certain metal ions in alkaline solutions, for example: Cu, Bi, Hg and Fe. Method based on the reduction of Cu ions (Sugar test Reduction) include the Fehling test and Benedict's test. Of these two methods, the Benedict Test It turns out it is better for urine examination because there are not many substances bother. Tests based on this method are not specific for glucose Other sugars or other substances that have reducing power will also do the same produces positive test results. This experiment was carried out twice with sample, namely: 1. Pathological urine provided by the lab 2. The student's own urine Ways of working: 1. Prepare five test tubes 2. Put 2.5 ml of Benedict's solution into each test tube. 3. Add four drops of the solution to be examined, pathological urine consisting of: Tube I : Glucose 0.3% Tube II : Glucose 1% Tube III : Glucose 5% IV tube : Galactose 1% V tube : Student urine 4. Mix well 5. Boil for 3 minutes, then cool. Note the color that occurs.