Biochem

TEST | REAGENTS | PROCEDURE | RATIONALE/PRINCIPLE | POSITIVE REACTION | PHENYLHYDRAZINE | phenylhydrazine | | The aldehyde groups of simple carbohydrates will react with phenylhydrazine but instead of yielding typical phenylhydrazones they make what is termed osazones where the OH group immediately adjacent to the keto group is oxidized to a keto group and it too adds phenylhydrazine to form the yellow to pale orange osazones that have definite melting points. So assignment of presumptive identity can be done my taking the melting point of a PURIFIED osazone from a purified carbohydrate. | yellow to pale orange osazone crystals | MUCIC ACID | 5N Nitric Acid | | Monosaccharides, upon treating with strong oxidizing agents such as nitric acid, yield saccharic acids. The saccharic acid obtained after the oxidation of galactose is insoluble and separates as gritty crystals. This acidic derivative is known as mucic acid, thus the name for the test. Galactose containing saccharides also reacts in a similar manner. | Formation of precipitate | ANTHRONE | Anthrone reagentGlacial acetic acid or 50% Sulfuric acid | Mix 1mL of glucose solution and 1mL of anthrone reagent. Stand for sometime and note the color produced immediately, and after ½ hour. If the solution is milky, dilute with glacial acetic acid or 50% sulphuric acid. Do the same with 5% galactose, maltose, fructose, sucrose, lactose, glycogen and starch. | Carbohydrates, in acidic condition, form furfural, which reacts to Anthrone which gives a bluish-green-coloured complex. | Blue colour formation | MOORE’S | Concentrated NaOH | Mix 1ml of 5% glucose and 0.5ml of concentrated NaOH. Boil and note the change of color and odor produced. Do the same with 5% galactose, maltose, fructose, lactose, sucrose, glycogen and starch. | When a solution of reducing sugar is heated with an alkali (NaOH), it turns yellow to orange and finally dark brown, liberating the odor of caramel. This is due to the liberation of