Quantitative Analysis of Carbohydrates

                                         Primary Concept                                                                                                                    

                         A carbohydrate is an organic compound with the general formula Cm(H2O)n, that is, consists only of carbon, hydrogen and oxygen, with the last two in the 2:1 atom ratio. Carbohydrates make up the bulk of organic substances on earth and perform numerous roles in living things.
The carbohydrates (saccharides) are divided into four chemical groups: monosaccharides, disaccharides, oligosaccharides and polysaccharides. Polysaccharides serve for the storage of energy (e.g., starch in plants and glycogen in animals) and as structural components (e.g., cellulose in plants and chitin in arthropods). Structural polysaccharides are frequently found in combination wit proteins (glycoproteins or mucoproteins) or lipids (lipopolysaccharides). The 5-carbon monosaccharide ribose is an important component of coenzymes (e.g., ATP, FAD and NAD) and the backbone of the genetic molecule known as RNA. The related deoxyribose is a component of DNA. Saccharides and their derivatives include many other important biomolecules that play key roles in the immune system, fertilization, preventing pathogenesis, blood clotting and development.
This experiment aims to introduce you with the identification of unknown carbohydrates. To gain maximum benefit, observations should be related, as far as possible, to the structure of the substances examined.

Some important points:-

1. Most of the tests and reactions described are not quantitative and volumes are approximate, despite these facts some tests do not work if quantities greatly in excess of those stated are used.

2. DO NOT place your pipettes in reagent bottles as this leads to contamination.

3. In most tests, it is important to apply a control test using water instead of the solution under examination. If you are in doubt about the result of a test, perform the reaction with a suitable known compound.

4. In this experiment, sugar samples are given in their solid state. To perform each procedure, you should prepare your own sugar solution by taking very small amounts of solid sugars.

5. When you need to boil your sample in a test tube, prepare a hot water in a large beaker and put your test tube inside the beaker. DO NOT forget to put boiling chips in the beaker.

TESTS ON CARBOHYDRATES

1. Molisch’s Test
2. Solubility Tests
3. Carbohydrates as Reducing Sugars
   • 3A. Fehling’s Test
   • 3B. Barfoed’s Test
   • 3C. Seliwanoff’s Test
   • 3D. Bial’s Test
4. Action of Alkali on Sugars
5. The Inversion of Sucrose
6. Iodine Test

Specification of Carbohydrate:-